First steps to adding code contracts.
* Cleaned up code generation visitor.
* Generalized code generation to include code expressions.
* Added prototypes for `requires`, `ensures`, `forall`, etc.
* Collection of specifications.
* TODO slicing for argument values to `requires` and `ensures`.
More progress on contracts.
* Computing function slice from requires call.
Code contracts prototype working!
Code contract slicing with loops.
Started to add `old` expressions.
Added `invariant`s, though not yet working right.
Loop invariants working.
Refactoring code contract extraction.
Regression tests for contracts.
Better contract extraction.
Cleaned up contract extraction a bit.
Quantified array expressions in ensures.
Small simplification.
Merge branch 'develop' into code-contracts

Conflicts:
	bin/smackverify.py
Merge branch 'code-contracts' into develop