CCSpriteFrameCache & CCAnimationCache Support.

[psineur]

1. Both CCAnimations & CCSpriteFrames are reused in many places in Cocos2D-iPhone to save memory.
   CCAnimate retains given CCAnimation instead of copying it.
   Also CCAnimation retains CCSpriteFrames, instead of copying them.
   This saves memory.
2. Currently CCSpriteFrameCache & CCAnimationCache doesn't get saved by AMC at all.
   So if you have 50 sprites and they share the same Animatiom from CCAnimationCache - their frames will be saved & loaded independently.
3. For editor - it will be very frustrating to change same animation in many places.
   As well as spriteFrames.

So here's the plan:

1. Save key, while saving CCAnimation or CCSpriteFrame if they exist in CCAnimationCache or CCSpriteFrameCache respectively
2. Always save all other properties when saving - even if key exist. Order of loading may vary, so we need that all CCAnimation or CCSPriteFrame dictionaryRepresentations can save themselves in corresponding cache.
3. When loading - check for existanse of CCAnimation or CCSPriteFrame in Cache by given key.
   If it doesnt exist - save it in cache on load.
   If it exist - always use cached version. But check for equality and log any inequality between cached and curLoading version.

This approach will give us ability to load only used parts of CCAnimationCache & CCSpriteFramesCache & reuse CCAnimations & CCSpriteFrames without using a lot of memory for the same objects.
Also it can speed up loading process.