Merge pull request #16 from colder/master

Do not create empty .so files at load time
Merge pull request #17 from colder/master

Bring scalaz3 up to dates with z3 4.3
Merge pull request #18 from colder/master

Collect Solvers much more often
Merge pull request #19 from colder/master

Deprecate softCheckCancel, replaced by interrupt
Use Z3_model_eval instead of the deprecated Z3_eval.

For BC we set reconstruct_models to false, but it might be
avantageous to turn it on and let Z3 complete partial models instead of
doing it ourselves later (i.e. in Leon).
Separate model_eval and eval, use model_eval in Z3Model.eval
Implement Z3Context.onError, called when z3 errors out.
Merge pull request #22 from colder/topic/eval

Use Z3_model_eval instead of the deprecated Z3_eval.
Merge pull request #21 from colder/topic/error-handlers

Implement Z3Context.onError, called when z3 errors out.
Two convenience functions on solvers.