fix for Ambiguity.equals
Adding hashCode implementation for Ambiguity and fixing one of the junit tests.
Merge pull request #681 from kframework/fix-for-ambiguity-equals

Fix for ambiguity equals
Updating the error message for unbound variables. Fixing issue #684.
Removing an extra space.
Updated definitions in 5_typed
Fixing set membership
Added test for set membership
Checkstyle problems
Checkstyle again
Merge pull request #687 from kframework/fixing-set-membership

Fixing set membership
Updated definitions in 5_typed
added all tests in 5_types
Merge branch '5_types-updated' of github.com:grosu/k into 5_types-updated
Update unification to apply mgu to lists, too
Made substituteList a function and added test for it.
Merge branch 'list-substitution' of https://github.com/kframework/k into 5_types-updated
fixes for Traian
Added Set substitution, too.
Modified test to test Set substitute