- minor refactoring
Merge branch 'gaf_4_develop' of https://github.com/CatalystApps/Cocos2dxGAFPlayer into gaf_4_develop

* minor refactoring
- fixed strange behavior of transparent pixels, if colorOffset.alpha > 0
Merge branch 'gaf_4_develop' of https://github.com/CatalystApps/Cocos2dxGAFPlayer into gaf_4_develop