added methods that were in cc2d-x.
Pulled down update to MonoGame
parity updates to the audio engine to match cc2dx
Merge branch 'master' of https://github.com/Cocos2DXNA/cocos2d-xna

Conflicts:
	cocos2d/denshion/CCSimpleAudioEngine.cs
Merge branch 'master' of https://github.com/Cocos2DXNA/cocos2d-xna