Formatting changes, update imports, other minor changes

[glass-ships]

This PR aims to include several auxiliary changes made in the Restructure PR #185, but without the restructure itself. Includes things like:

• Formatting
• Updating imports
• Renaming tests to the pytest standard of test_<test name>.py

along with some other small random changes.

Should be overall an unobtrusive set of changes.

[glass-ships]

Unclear why a few doc tests are failing.

Fixed

[bmaranville]

I honestly don't know what this file is for.

[glass-ships]

the only other place pylit gets used is in gentut.py, but I dont think it references this file. safe to delete?

[bmaranville]

I don't completely understand how the documentation gets created, tbh. Is there any chance sphinx makes stuff from here?

[glass-ships]

I believe sphinx references conf.py which calls gentut.py to generate the tutorials. but gentut.py just imports pylit, which is just a direct copy of an old version of https://codeberg.org/milde/pylit/src/branch/master/pylit.py

We can either leave pylit.py as it is, or delete it and add pylit to the pyproject.toml as a dev dependency.

I tested the latter option, and it seems to work just fine, so either option would be fine. Dealer's choice

[bmaranville]

Looks really good - a few minor changes suggested inline.

[glass-ships]

Sweet - comments have been addressed!