Using package encoding

[julianayang777]

• Add a flag -p to the command wl test in order to print the results of the execution in stdout.
• Refactor EvalSymbolic.ml to use the package encoding instead of querying directly with z3 through Translator.ml
  • Refactor heap modules to also use encoding types.

Note that: We did not distinguish Val (Loc n)and Val (Integer n) of type Term.t when evaluating to encoding types, both were evaluated to Val (Int n).

[filipeom]

Just a few small changes. But it looks great! Can you raise an issue in encoding due to missing simplifications I outline?

[julianayang777]

Ok, I will add these issues about simplifications and the one about the concrete execution.