Introduce finer save structure

[JoeyBF]

This should solve #123

[JoeyBF]

@hoodmane Any thoughts on this? This is getting relevant again as we're prepping for more computations soon.

I was thinking, since this isn't backwards-compatible with the current save format anyway (although fairly close), that this would also be a good time to rename the files themselves. For many purposes, it's more convenient to have n_s_kind than s_t_kind. One issue is that in theory stems can be negative, but there's simple fixes for that, e.g. printing -i as mi.

[hoodmane]

Sorry for the super long delay in review. I'll try to take a look soon, but if you need it feel free to merge. It would be nice if we could get someone else to contribute/review changes. But it's hard.

[hoodmane]

printing -i as mi

Maybe kind_-1_7 would be fine too.

[JoeyBF]

Sorry for the super long delay in review.

No worries! If it had been urgent I would have pinged you earlier but I get that other things get in the way sometimes.

It would be nice if we could get someone else to contribute/review changes. But it's hard.

Agreed. It seems like the intersection of people who are proficient in both Rust and computational homotopy theory isn't very big, or maybe they prefer spending their time on their own projects.

Maybe kind_-1_7 would be fine too.

Yeah but I'm really uneasy about special characters like that in filenames. Also, I tried putting the kind first but it breaks one of the tests in a nontrivial way because it makes the filename harder to parse. If we look at segments delimited by '_', then the stem is either the second or third segment, because kinds sometimes have underscores in their name. It's also either the second to last or third to last, because sometimes we have an extra _idx tacked on at the end. I created #180 to test that out.