Run black and isort on entire repo

[APJansen]

Feel free to delete, I don't oversee whether this may be more of a headache than it solves, but I just wanted to get rid of all the diffs that are just from applying black or isort.
So here I did only that, in the top level of the repo, black . and isort ..

There was one file that black couldn't reformat, due to this line which apparently uses Python 2 syntax. I didn't touch that, literally only did the 2 commands above.

[scarlehoff]

hi @APJansen this cannot be done now because it will create a mess for many branches.

Also, we already did it in the past and people kept on forgetting to add it so the only solution is to add a workflow that lints the code and reminds the user to do it (I'd rather not do it automatically)

[RoyStegeman]

We could urge people to use pre-commit and add a dot file with the settings we want?