v0.4.3 (README++)
improve diff highlighting.
remove the use of git
v0.4.1 - typofix!
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.
v0.3.1 with python 3.7

- 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.