cocos2d/cocos2d-x — pull request #3189 by tiantian20007 (2013-07-18 10:14:33+00:00)
Title: Also removeUnusedSpriteFrames when purgeCachedData;

When a game running on iOS get a memory warning, cocos2d::CCDirector::sharedDirector()->purgeCachedData() will be called.
However, most case, we use CCSpriteFrame which will retain textures.
So we also need to removeUnusedSpriteFrames when purgeCachedData.