rm decision jh GiveUp related code
refactoring justification_heuristic code
decision/: justification: refactor ITE out
decision/ : jh: refactor embedded ITE, other minor

other minor: cleanup some remaning fragments of GiveUpException(),
hopefully all is gone now.
decision: jh: more refactoring (.h->.cpp, xor/iff)
Merge pull request #6 from kbansal/decNewoptions

decision/ code refactoring