meetbot: Line length, linting, tweaks, fixes

[half-duplex]

This should satisfy the easy scrutinizer, flake8, and human complaints, and removes a couple TODOs (display durations in minutes instead of seconds).

[dgw]

So, this isn't a "request changes" per se, because I'm perfectly happy with the diff as-is. However, there are some "extra mile" type tweaks that I called out in line notes (most of which are just examples of issues that occur several times each throughout the code). If you're feeling extra "fix-it-y", have at these! 😸

[Exirel]

I'm not particulary fan of replacing 'string' by "string". Quite the opposite, actually.

Otherwise, nice work.

[Exirel]

The diff isn't the easiest to read. I'd have love separated and atomic commits to review it, change by change (lower_case function in one commit, proper import in another one, log refactoring after that, etc.).

But that'll do. I didn't review the feature itself, I assume @half-duplex make it work as before.

[half-duplex]

(Switched back to sopel.web to remove #1616 dependency and added a \n after </html>)
I only realized 2/3 of the way through your comments that the changes were significant and dividable enough it should be multiple, apologies.
I did test it about as comprehensively as I can having not used it before (start meeting, run commands, end meeting, logs look sane).

[Exirel]

I only realized 2/3 of the way through your comments that the changes were significant and dividable enough it should be multiple, apologies.

Still a great work! Thank you. 👍