Tracked objects now have their type information tracked with them.

Enhanced summaries for ObjC methods to include the type information of the receiver.

Used the enhanced summaries to support the idiom that NSWindow owns itself (it sends a release message to itself upon close).

Added some comments.

Did some cleanups with the checker logic using operator overloading (reduced redundant code which I was concerned about being the source of bugs).

llvm-svn: 52741