Fixed logic for selecting model_compress param.

Merge pull request boogie-org#189 from michael-emmi/z3-params

Using old Z3 model_compress parameter for Dafny.

further cleanup of refinement instrumentation

clean up of refinement checking

Merge pull request boogie-org#183 from michael-emmi/restore-total-use…

…r-time

Restore TotalUserTime field removed by 714d5a0.

small fix to convert a conditional into a debug assert

small refactoring in refinement instrumentation code

Merge branch 'master' of github.com:boogie-org/boogie

Update README.md

Merge pull request boogie-org#186 from michael-emmi/z3-parameters

Updating Z3 model_compress parameter.