force the non-use of the MSBuild engine per https://bugzilla.xamarin.com/show_bug.cgi?id=14539 so that MonoMac build will continue to work properly on recently updated Xamarin Studio.
Merge branch 'master' of https://github.com/Cocos2DXNA/cocos2d-xna
fixed concurrent mod that could result in a null timer
helper method to scale a sprite according to a size.
another instance of a NPE in the scheduler during a multi-threaded async load.
Added ability to create a sprite sheet from a list of frames.
Pulled down update to MonoGame
fix for windows 8 build missing a test file.
added an action way of handling tween operations.
added auto-alias generation to the sprite frame lookup
fixed CCTMXLayer ZOrder. "TMX Ortho vertexZ" and "TMX Iso VertexZ" works now.
possible load raw string assets. Fixed GetAssetStream.
possible use CCNode in background