Add pre commit + black

[nstarman]

A maintainer will need to turn on pre-commit.ci to enforce pre-commit in the CI.

[rgommers]

Thanks @nstarman. The black reformatting looks like an improvement, in particular the signatures using one line per argument. I'm +1 on that change.

The larger style problem in this repo is that the docstring text doesn't have proper line breaks. I've looked at that before and unfortunately there's no tool that can deal with that automatically.

For pre-commit: I'd be fine with adding a check to CI (either pre-commit or simply black running in a CI job). However, I'd much prefer to get no bot PRs, those are just noise for both contributors watching the repo and in the commit history. Can we get this without autoupdate_schedule?

[nstarman]

The larger style problem in this repo is that the docstring text doesn't have proper line breaks. I've looked at that before and unfortunately there's no tool that can deal with that automatically.

At Astropy we've just started to use PyQA's docformatter in our pre-commit. docformatter can do some text regularization automatically.

For pre-commit: I'd be fine with adding a check to CI (either pre-commit or simply black running in a CI job). However, I'd much prefer to get no bot PRs, those are just noise for both contributors watching the repo and in the commit history. Can we get this without autoupdate_schedule?

Yes, using the GH action
https://pre-commit.ci/lite.html
I can add this to the PR.

[rgommers]

Thanks! I tried some tools last year, but docformatter seems to have seen very active development recently - will try again.

[rgommers]

Thanks @nstarman, this is looking pretty good to me now. Only one more comment.

[rgommers]

LGTM now, thanks a lot @nstarman.

I'll plan to squash-merge this very soon, and then push a follow-up commit with a new .git-blame-ignore-revs entry.