Making the local FTCSprite ivars weak
Instruments was complaining about a retain cycle
http://monosnap.com/image/6UVIyHRFXZSRLdnDDlP8yxSYk

The ivars are __strong as explained here:
http://clang.llvm.org/docs/AutomaticReferenceCounting.html#ownership-inference
Merge pull request #1 from ribeto/FTCSprite_weak_vars

Making the local FTCSprite ivars weak