Predictable module names (fixes #469)

[oyvindberg]

Problem

It's almost impossible to map Javascript module names to the currently generated ST object/package names in your head.

There is a 1-1 correspondence, but it's impossible to understand. Let's finally fix this mistake!

I know this will lead to "uglier"/longer module names, this has been discussed various times in the past, but the encoding needs to become easier to understand.

Keep old behavior

add stShortModuleNames (for sbt plugin) and --shortModuleNames for CLI which reverts to old behaviour.

Note that this old behaviour is deprecated. I don't intend to remove it for a long while, but I won't put any effort into maintaining it either.

Example

Here is a typical example of what it'll look like - see how clearly you can see the hierarchy even though it's flattened.

[oyvindberg]

One possible problem is that this might trigger windows long file name errors, those were somewhat common in the past. I think if that happens let's rather compress the file names on windows and keep the package names correct.

[nafg]

With class files the packages will always correspond to directories so not sure that is an option

[oyvindberg]

@nafg to gauge the problem I wrote a script to traverse all the jar files for a full CI build, looking for the longest class files. The longest is a trait produced from the fake string literals:

typings/octokitPluginRestEndpointMethods/octokitPluginRestEndpointMethodsStrings$DELETE$u0020SlashreposSlashLeftcurlybracketownerRightcurlybracketSlashLeftcurlybracketrepoRightcurlybracketSlashactionsSlashcachesLeftcurlybracketQuestionmarkkeyCommarefRightcurlybracket.class

This will blow up the windows path budget in any case, weighing in at 274 chars. On the bright side, this should be gone after #487, so let's dig up the longest class class file name after removing those of fake strings:

typings/officeUiFabricReact/libComponentsPickersPeoplePickerPeoplePickerItemsPeoplePickerItemDottypesMod$IPeoplePickerItemSelectedSubComponentStyles$IPeoplePickerItemSelectedSubComponentStylesMutableBuilder$.class

214 chars. Will very likely fail on windows, given that there is a semi-long prefix added to this.

If we change the naming pattern for the builder class, it could come out like this instead:

typings/officeUiFabricReact/libComponentsPickersPeoplePickerPeoplePickerItemsPeoplePickerItemDottypesMod$IPeoplePickerItemSelectedSubComponentStyles$MutableBuilder$.class

That's 171 chars. borderline possible to compile on windows.

[oyvindberg]

Then there are anonymous traits, object types not named in TS.

typings/reactNativePaper/anon/CallHasLabelAccessibilityLabelPageNumberOfPagesOnPageChangeStyleThemeShowFastPaginationControlsNumberOfItemsPerPageListNumberOfItemsPerPageOnItemsPerPageChangeSelectPageDropdownLabelSelectPageDropdownAccessibilityLabelRest.class

260 chars. may also want to enforce length of these traits, without introducing name collisions. I thought that was already in place honestly, but there's probably a bug in that code

[FabioPinheiro]

Thanks, @oyvindberg for pointing out where the changes come from.
I tested the flag and stShortModuleNames keeps all the code compiling with no change (on my project).
Either way, I will probably change the code and not use the flag.