Update FlxG.version
Use a buUse a build matrix for Travis tests + test HTML5
FlxTextFormat doc tweak
FlxKeyboard: fix function keys going from F2-F13 on cpp

Workaround for a Haxe bug. https://groups.google.com/d/msg/haxeflixel/WcSH8e7mGH8/nZywIYhsvGQJ
SoundFrontEnd.play(): fix volume not being respected, remove unused _soundTransform
FlxTilemap: additional safety check to prevent possible crashes
Preparation for version 3.3.1