Set maxzoom to 20 by default

[peterqliu]

for parity with gl-js

snippet

[1ec5]

Does gl-js have a library-level maximum zoom level, or does it only care what the tile source says the maximum is?

[peterqliu]

Has default max of 20, but configurable

[1ec5]

That seems like a reasonable way to do it. Anyone know why it isn’t configurable in the first place?

[kkaefer]

It was never implemented. No reason not to implement it though.

[mb12]

Currently Collison::max placement depth is hard coded to 3 i.e. for a source with Max zoom 15, Symbols are placed until zoom 18. This limitation will go away once @ansis changes for label placement are merged into master.

[jfirebaugh]

Duplicate of #509.