fix bugs in CCDictionary & platform/win32/CCImage.cpp::setFont, according to BitWave's codereview.
fix bugs in CCDictionary::objectForKey(int/string)
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20

Conflicts:
	cocos2dx/cocoa/CCDictionary.cpp
	cocos2dx/platform/win32/CCImage.cpp
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
Add a sample doxygen sample in CCSprite.h and CCProtocol.h
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
fix typos in doxygen of CCSprite and CCProtocol
Merge pull request #1840 from walzer/gles20

Doxygen sample in CCSprite.h