Merge branch 'audio-rework' into cne-dev

# Conflicts:
#	flixel/sound/FlxSound.hx
#	flixel/sound/FlxSoundGroup.hx
#	flixel/system/frontEnds/SoundFrontEnd.hx
#	flixel/system/macros/FlxDefines.hx

Author: Raltyro

flixel/FlxGame.hx

@@ -593,6 +593,11 @@ class FlxGame extends Sprite
 			_state.destroy();
 
 
+		// sound datas too.
+		#if FLX_SOUND_SYSTEM
+		FlxG.sound.clearCache();
+		#end
+
 		// Finally assign and create the new state
 		_state = _nextState.createInstance();
 		_state._constructor = _nextState.getConstructor();