Adding formatters for several useful Objective-C/Cocoa data types. The new...

Adding formatters for several useful Objective-C/Cocoa data types. The new categories are not enabled at startup, but can be manually activated if desired.
Adding new API calls to SBValue to be able to retrieve the associated formatters
Some refactoring to FormatNavigator::Get() in order to shrink its size down to more manageable terms (a future, massive, refactoring effort will still be needed)
Test cases added for the above

llvm-svn: 150784