Merge pull request #337 from gena-m/master

CCTextureCache.AddImageAsync and fixed Issue #317
fixup of the license and misc typo fixes in the readme.
added [0,1] constraint on the tension as this is required for hermitian curves.
undo of opacity change for default color init
fix for the content size of a menu. prior was always the full size of the window. now it computes the size when the items are aligned.
Merge pull request #338 from Cocos2DXNA/CCMENU_CONTENTSIZE_FIX

fix for the content size of a menu
Merge pull request #339 from gena-m/master

revert CCLayerColor initialization
RasterizerStates Cache