BetterTerrainAddon-1.4.3

• Updated to API 1.1.1
• Fixed an issue causing noise generators to not respect the seed after the first world generated after booting the game.
• Fixed an issue where attempting to create a vanilla world type with BTA and deco installed would create the wrong world type if you did not toggle deco beforehand.
• Fixed an issue where beta and skylands worlds generated far too few trees.

BetterTerrainAddon-1.4.2

• Fixed an issue where any changes using random generators would result in the terrain noise being initialized in a different way, causing large world seams if anything was changed (to the point where unrelated mods could affect the generation). This only affected 1.4.X worlds so older worlds are fine. However, the fix for this necessitated causing one more world seam, so any worlds that were generated with 1.4.0 or 1.4.1 will have different generation now. I apologize for any inconvenience this may have caused, but damage should be minimal given the same day release and the fact that old worlds were unaffected by the bug as they do not use the new generator system that 1.4.X worlds do.
• Fixed an issue where frozen beaches and red sand beaches would spawn normal beaches at their edges.

BetterTerrainAddon-1.4.1

• Fixed an issue where some of the changes to badlands edges were not checking the world version and thus could create seams.

BetterTerrainAddon-1.4.0

• Added a new surface builder system which allows much finer control over how biomes are generated. This includes incorporation of K.JPG's OpenSimplex2 (more information in credits section of OP).
• Added areas of podzol and coarse dirt to coniferous forests and snowy coniferous forests in new worlds when deco is enabled.
• Completely overhauled badlands in new worlds. They now match vanilla badlands much more closely. This is detailed more in the changes below.
• Changed badlands plateaus to actually be plateaus instead of just normal mountains.
• Changed badlands plateaus to use normal terracotta as the topmost block at high elevations.
• Changed badlands plateaus to spawn occasional wooded sections atop the plateaus.
• Changed how terracotta layers generate in badlands to be more common and to be random based on the world seed instead of fixed and periodic. This only affects new worlds.
• Changed badlands plateau to use regular badlands as its edge biome rather than having a dedicated badlands edge. Badlands edge will continue to generate in existing worlds but has been deprecated for old worlds.
• Changed grass and foliage color of badlands.
• Changed (reduced) the width of badlands edges in new worlds.
• Changed (reduced) the number of trees slightly in coniferous forest variants in new worlds.
• Changed how sandy shorelines generate to use simplex noise instead of perlin to remove occasional directional artifacting. This only affects new worlds.
• Changed how grass generates in outback to make it based on simplex noise instead of random decorators. This only affects new worlds.
• Changed how surface stone generates in arid forest, chaparral, and shield in new worlds in the same way as outback grass above.
• Changed how trees generate in alpine, steppe, orchard, heathland, coniferous forest, snowy coniferous forest, and icy peaks in new worlds. Instead of relying on sub-biomes to modify tree type or density, tree generation is now based on simplex noise. As a part of this, aspen grove, wooded steppe, orchard clearing, heathland woods, coniferous forest clearing, snowy coniferous forest clearing, and forested icy peaks have been deprecated. These sub-biomes wil continue to generate in existing worlds but have been removed from new worlds.
• Changed alpine to generate fewer trees at high elevations in new worlds.
• Changed oasis (for real this time!) and steppe to not spawn sandy shorelines in new worlds.
• Fixed an issue where large oak trees (the vanilla ones) would sometimes all generate at the exact same size in an entire biome.
• Fixed an issue where beaches were generating with grass. This may cause surface material seams but can be manually fixed relatively easily (or old chunks can be deleted in MCEdit and they will regenerate)
• Fixed an issue where frozen beaches were generating in places they shouldn't. Existing frozen beaches will revert to normal beaches.

BetterTerrainAddon-1.3.4

• Updated to Extended Addon API 1.1.0.

BetterTerrainAddon-1.3.3

• Added new red sandstone desert pyramids which can spawn in outback and badlands.
• Added the ability to double click biomes in the biome configuration menu to toggle whether they are enabled.
• Changed world configuration to have deco generation enabled by default if deco is also installed. Deco generation may still be disabled if you wish.
• Changed world configuration so that enabling deco automatically enables all deco exclusive biomes. Previously it was possible to enable deco but then not get deco biomes because you had to specifically re-enable them.
• Fixed an issue where frozen springs, plains, temperate forest, and patagonia were not properly generating reeds.
• Fixed an issue where the game would crash if spaces were present in the generator options string.

BetterTerrainAddon-1.3.2

• Added edge variants to rainforest and jungle in new worlds which have slightly less dense vegetation, and which will not spawn melons. This helps provide a transition into the heavy vegetation of these biomes, and makes easy melons harder to obtain by preventing them from spawning at the very edge of these jungle variants.
• Added an edge variant to tropics in new worlds, causing it to be much more likely to spawn as islands instead of connecting to neighboring biomes. When tropics does connect via land, it is likely to do so through sandy beaches.
• Added a BTA version of the vanilla beach, for the same reason as I previously did the same for rivers. This again will not affect anything in your world, but simply allows me to do more with beaches down the line if I wish.
• Added frozen beaches. Snowy woods, frozen springs, siberia, and tundra will now spawn frozen beaches when connecting with oceans. This only affects new worlds.
• Changed how reeds generate in frozen springs slightly to make them a bit more common.
• Changed (increased) the thickness of the border created by all edge variants. This only affects new worlds.
• Changed (increased) the chance of melons spawning in jungle, rainforest, and mangal to offset the large amount of vegetation present (or water in the case of mangal) which could prevent them from spawning.
• Changed (decreased) the chance of melons spawning in tropics given that it is easier to traverse than other jungle variants and has less vegetation.
• Fixed an issue where the game would crash when trying to smooth between climates when no biomes of the transition climate were enabled. The game will now not attempt to smooth climates if no biomes are available for smoothing.
• Fixed an issue where particularly wide rivers could generate with a standard river along the center even if the rest of the river was a different variant. This was most notable as a change in water color but could also show up as missing ice, mismatching riverbed material, or having a random spot of rain in the middle of the river in desert variants.

BetterTerrainAddon-1.3.1

• Fixed an issue causing the game to generate highlands instead of mountains. Any highlands generated in the previous release will be converted to mountains. Worlds created before 1.3.0 will revert to exactly how they were before 1.3.0. This may cause slight biome color seams in 1.3.0 worlds but given that the two biomes have exactly the same terrain generation will not cause any terrain seams. MCEdit may be used to replace biome id 125 with 145 to make the biomes colors match what they should, or MCEdit can be used to delete any of those chunks and the game will generate them correctly the next time you are in the area.
• Fixed an issue where frozen springs would still generate cherry trees if deco was installed but deco world generation was disabled.

BetterTerrainAddon-1.3.0

• Added climate zones. This can be configured at world creation, and is enabled by default. This means biomes will now be clustered according to their climate: Snowy, cold, temperate, tropical, or arid. Climates are randomly distributed, then smoothed to prevent disjointed transitions between climates. A full list of which biomes belong to which climate is available in the OP.
• Added height-dependent snowfall in cold biomes. Snow will fall anywhere in these biomes above y=95. This only affects new worlds.
• Added frozen springs as a new snowy biome which can generate reeds.
• Added boreal forest as a new cold taiga variant (wolves) and renamed the old boreal forest to temperate forest.
• Added mangal (mangrove forest) as a new temperate jungle variant (temples, jungle spiders, reeds).
• Added arid forest as a new arid forest variant (duh). Arid forest also replaces woods as a sub-biome for plains in new worlds.
• Added shield as a new cold taiga variant (wolves).
• Added brushland as a new cold plains variant (villages, pumpkins).
• Added highlands as a new temperate mountain variant (emeralds, silverfish).
• Added pockets of water to wetlands, willow grove, jungle, and rainforest, similar to how vanilla generates water in jungles and swamps. This only affects new worlds.
• Added small oasis pockets inside lush deserts in addition to the large ones. This only affects new worlds.
• Added the ability for reeds to spawn in patagonia, plains, and temperate forest. In the new climate distribution system it was possible to have extremely large distances between biomes which could spawn reeds, which could be a problem given how vital they are early game. So this, combined with frozen springs above, ensures every climate is capable of spawning reeds in at least one biome. However, tropical climates remain where reeds can be found most commonly.
• Added the ability for melons to spawn on the surface in jungle variants (jungle, rainforest, tropics, mangal).
• Added the ability for emeralds and silverfish to spawn in dunes.
• Added a hook for other addons to add their own biomes to BTA world generation.
• Changed configuration menu to have biome configration on its own page.
• Changed the formatting of the generator options string. The old format will still be processed correctly for old worlds but will not contain any new options. The new format ignores whitespace, has labels for all options, and is order-agnostic.
• Changed ocean size configuration to be a scale from 1 (off) to 10 (vanilla), defaulting to 5.
• Changed (increased) possible biome size ranges to 0.5x to 4x vanilla (Original BTA was 2x, vanilla large biomes is 4x). As a part of this, small world types have been deprecated as biome size information is now handled through generator options. These world types will continue to function for existing worlds but may no longer be created.
• Changed the default biome size to vanilla sized biomes as the new climate zone system tends to spread out dissimilar biomes further than before.
• Changed the display name of a few biomes in world configuration to match the generic name rather than specific sub-biome names. Internal biome names remain the same, and are still listed in the OP (internal biome names only concern texture pack authors using MCPatcher).
• Changed oases to no longer spawn sand from better shorelines. This only affects new worlds.
• Changed biome colors for plains and steppe.
• Changed tundra to no longer be a valid biome for world spawn.
• Fixed an issue where frozen rivers weren't frozen. Any which have generated in your world in the last release that weren't frozen will naturally refreeze as you spend time near them. The biome locations were correct, just not the precipitation data.
• Fixed an issue where wetland hills and willow grove hills would spawn standard rivers within them and not jungle rivers, leading to mismatched water color.
• Fixed an issue where beta and skylands world types always generated vanilla sized biomes, regardless of world configuration settings.

BetterTerrainAddon-1.2.1

• Added plains, modified from the vanilla version.
• Added BTA versions of river and frozen river. This does nothing except allow me to control how decorations spawn in them.(most notably allowing me to limit vanilla sand spawning for better shorelines).
• Added the ability for desert temples to spawn in steppes.
• Changed how version compatibility is handled internally to have finer control. This largely only concerns server owners and is detailed in the server section of the OP.
• Changed the biome colors of grasslands slightly.
• Changed the position of buttons in the BTA world configuration menu.
• Fixed an issue where badlands edge, badlands river, outback river, and red sand beach were generating regular sand near sea level instead of red sand when better shorelines were enabled.
• Fixed an issue where toggling buttons in beta or skylands configuration would change the text of the oceans button to on, despite the fact that those world types cannot generate oceans.
• Fixed an issue where the better shorelines button was enabled when creating beta and skylands worlds, despite the setting not affecting those world types (beta always has it turned on, and there is no sea level in skylands to generate shores).
• Fixed an issue where the setting for better shorelines was always being set to true at world creation regardless of the state of the button in the configuration menu.
• Fixed an issue where sand would not generate underwater at all in legacy (pre 1.2.0) worlds.
• Fixed an issue where jungle hills would spawn standard rivers within them and not jungle rivers, leading to mismatched water color.
• Fixed an issue where jungle rivers did not spawn enough sand when using vanilla sand generation.
• Fixed an issue where willow groves were not able to spawn witch huts, reeds, or slimes.