Merge pull request #2 from HaxeFlixel/dev

Updating to Match latest HaxeFlixel Version
FlxTypedButton: Change callback type to Void->Void to avoid Reflection, remove FlxButtonEvent.callbackParams, closes #805
Remove remaining Dynamic's from FlxTypedButton, also use Void->Void for FlxSystemButton
Merge branch 'dev' of https://github.com/HaxeFlixel/flixel into ButtonCallback
FlxVirtualPad and VCR compatibility with button callback changes
Merge pull request #806 from Gama11/ButtonCallback

FlxTypedButton: Change callback type to Void->Void to avoid Reflection, closes #805
Revert the hash creation of TileShetExt.hx getKey() because it was causing hash collisions affecting this issue https://github.com/HaxeFlixel/flixel-addons/issues/15
Merge pull request #816 from mrcdk/fix_flixel_addons_15

Revert the hash creation of TileShetExt.hx getKey()
FlxMouse: remove Show param from registerNativeCursor()
README.md: link to haxeflixel.com with the logo
Remove FlxSoundUtil

Doesn't make sense to have a util class for a single function that could be replaced by a simple FlxTimer
A bit of cleanup for flixel.util.loaders classes
Improved docs for FlxBasic.cameras
Update outdated docs on FlxG.cameras
Improve error msg in CameraFrontEnd.remove() and turn it into a warning
Improve the For Developers section

Include links to the relevant and more detailed documentation about contributing to the project.
override FlxText's set_cachedGraphics
FlxPreloader: Fix flixel version text
Initialize CachedGraphics.useCount for neko (thanks @MrCdK)
Add null check to BitmapFrontEnd.remove() to fix a neko crash (thanks @MrCdK)