Reformat using black

[matt-kempster]

The black autoformatter (https://github.com/psf/blackhttps://github.com/psf/black) is a common way to unify the style of a project.

The things that are substantially different:

• Spaces instead of tabs
• Double-quotes instead of single-quotes
• Lines limited to 88 characters
• Newlines used only when needed

There are a few things we can manually improve via "magic commas" (psf/black#1288) like matrices, but I think this is a good start.

Feel free to reject this PR :) I just figured I'd introduce it to make it a bit easier for people to contribute to a consistent style.

[Dragorn421]

Thanks for the PR! Yes we do want to format the repo. I'm personally a black fan and I got @thecozies somewhat convinced 😄

However we think doing it bits at a time, because it's too much to review as a single thing, and we'd like to tweak some files as they get formatted (moving stuff around, adding commas), maybe ignore some files (e.g. f3d_constants.py).

So again we'd rather do it in chunks instead of all at once.

If you had something specific in mind to contribute on, but were astonished at how poorly formatted the code is, and want to have specific files formatted before working on them, feel free to submit a PR with partial formatting (only the files or bits that you intend to edit)

I'll open an issue related to the formatting to keep track of things