Update z3 which would hold on certain ADT definitions

More info at https://z3.codeplex.com/workitem/113
Add List.take and List.drop, unproven, for convenience in benchmarks
Base implementation of an SMTLib printer/solver
Improve/Fix SMTLib solvers

- Implement smt and smt-z3/smt-cvc4 as options for --solvers

- Uses a main solver sources for verification/CLP, taking into account
  --solvers

- Implement Z3-SMT sets

- Add tests for Z3-SMT