GRState:

- Remove ConstNotEq from GRState/GRStateManager (!= tracking uses GDM instead).
- GRStateManager now can book-keep "contexts" (e.g., factory objects) for uses
  with data elements stored into the GDM.
- Refactor pretty-printing of states to use GRState::Printer objects
  exclusively. This removed a huge amount of pretty-printing logic from
  GRExprEngine.

CFRefCount
- Simplified some API calls based on refinements to the GDM api.

llvm-svn: 54835