improve diff highlighting.
v0.4.0 - varia and cosmit
clean import, reduce log and better progress bar.
add tests file ex.py and test.py...
add 'mutation apply UID'.
do not show mutation during test, but during replay.
- Check the database exist.
- play_test_tests: pass extra argument `command` for replay...
- Specify numprocesses only when max workers > 1.
- During `play` store command for re-use in `replay`.
- Count mutation failures.
- replay: re-use command.
mutation: ignore files without coverage.
alpha is the time taken to run the tests
sort files by size before computing mutations...
... it is better, because big files will take a lot of time to
complete, whereas small file will do fast, that way we can maximaze
the time where the pool is busy.