Some refactoring

Move handling of --try-run out of Test.Hspec.Runner.Eval
Minor refactoring
Rename progressHandler to progressCallback
Simplify eval code (and make it faster)
Minor refactoring
Some more refactoring
Isolate parallelization code
Depend on base-compat
Revert "Depend on base-compat"

This reverts commit 5a0f996ba67f69bcb4704c866b3781ccc796e679.
Depend on QuickCheck 2.7
Depend on hspec-meta >= 1.9.0
Use Random instance of Int for newSeed
Compatibility with QuickCheck >= 2.5.1 (see #166)
Fix warning
Bump version
Require hspec-meta >= 1.9.1
Make tests work with older versions of QuickCheck
Remove mk-sdist.sh
Fix failing test
Fix warning