Replace start '$' to '_'

This patch avoids "Field names starting with a dollar are not allowed" error.
Merge branch 'development' of github.com:HaxeFoundation/haxe into development
Enhance name handling for Java platform.

 * Classes with a encoded file name are supported, e.g. packageName/SingletonClass$.class, packageName/SingletonClass$$plus$.class
 * Methods start with a dollar are supported.
[java] Create aliases for simple imported inner classes
Replace "_" to "__" when escaping Java names.
Allow aliases for names that contain mutiple dollars.
Convert first character of class name to upper case
Tests for new name escaping
Merge branch 'development' of github.com:HaxeFoundation/haxe into strict-name-encoding
Merge branch 'development' of github.com:HaxeFoundation/haxe into strict-name-encoding
Allow '$' in method names
Merge branch 'development' of github.com:HaxeFoundation/haxe into strict-name-encoding
[cpp] export global functions as special case
fix various parts of haxe.xml.Printer
dodge strange empty enum error
Update JSGenApi.hx
Update typer.ml
Merge pull request #3193 from porfirioribeiro/patch-1

Custom js gen feature support
flash.Vector is only available on flash 10+ (closes #3195)
drop var/assign/return expression when TContinue/TBreak is used as its value (closes #3197)