Bugs:
* ffd animation was ignoring last frame. Lua has 1-based arrays, so last frame is `frames[#frames]`, not `frames[#frames - 1]`
* nil exception when accessing array lenght after it's confirmed nil. First we check if `not vertices` and in next statement we're trying to check for it's length, which causes exception. This code is logically equivalent to code before but avoids checking potentially nil array for length.
There are no longer separate animation files, they are now inside the skeleton file. This means there is just one file to manage, which is cleaner. Now that animations are stored in SkeletonData, they can be looked up by name which leads to cleaner runtime APIs.
cocos2d and cocos2d-x runtimes got a cleaner ObjC/C++ API.
