added SoundPool, removed deprecated methods
SoundPool contains the all methods to play sound. Right now you can only play music clips in SoundPool. Very specific sounds shouln't be placed in SoundPool instead they should be put into the calling class.
I removed some deprecated methods (i.e. getAbsoluteX() and getAbsoluteY()) as well as some unused methods (Main.getGraphicsDevice(), ...). Finally I removed DeprecatedButton as it isn't needed.