converted Sparrow from ARC to MRC
Merge branch 'master' of git://github.com/racarone/Sparrow-S into racarone-master
using 'dispatchEventWith:' methods for ADDED/REMOVED events
re-added SparrowClass_Internal
added some MRC API documentation to 'removeEventListenerForType:block'
optimized broadcast of enter frame event
implemented limited OpenGL state caching
minor optimizations
removed obsolete comment
replaced id with instancetype for methods that return an instance of the receiving class’s type
now using NS_ENUM for enums
replace literal string macros with NSString const*
removed all unnecessary @synthesize
optimized render state stack
SPTouch now retains target (closes #16)
extern strings now reflect their name
blend modes are now extern const uint
disable blend completely on SPBlendModeNone
text field exern const replacements
method fomatting is now consistent