just a reminder for myself to make background work again

(don't know why this functionality has been removed)
FlxTypedButton: use less crazy logic for setting the frameIndex, closes #1026
FlxBitmapTextField works on flash now, but need further improvement
one less check in bitmap text
Remove the "dev" tag from FlxG.version
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
Merge branch 'master' of https://github.com/HaxeFlixel/flixel into dev