ARC and Blocks

Version 1.2.0 of CDEvents introduces support for blocks and the library has also been converted into using ARC (automatic reference counting). Because of this the OS X deployment target has been raised to 10.6 and garbage collection has been dropped.

A few bugs and issues has also been squashed 🌟

Thanks to JustSid, tonyxiao and dwlnetnl for their contributions and helping to squash some bugs as well as improve the framework.

The API documentation has also been updated.