[Checkers] More Recent Check-ins

[Mahmood Ali]

Hi guys,

In the last few check-ins,  I made two changes:

1. Introduction of the meta-annotations and graph type checker.
Currently, BaseTypeChecker uses annotations and meta-annotations to  
construct the type qualifier hierarchy.  Interned, NonNull, and Test  
checkers all use it now!
Please review the code.  I especially recommend that you rename the  
classes.  I was a bit running out of names and I am pretty sure that  
you can be more creative and get some names that are more trivial.

2. FactoryTestChecker is in!
It's the class that implements the first testing proposal I sent  
yesterday.  It allows for testing getAnnotatedTypes() independently.

- Mahmood