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
Fix crash for call runAnimation() in CCBAnimationManagerDelegate::completedAnimationSequenceNamed; Set mRunningSequence to NULL before any runAnimation() call;
Merge branch 'gles20' of https://github.com/cocos2d/cocos2d-x into gles20
add WebP support
fix some issues
fix for mac
fix for win32
update libwebp to 2.1
add support RGB888, RGB565,RGBA4444