shrink repo storage size by rewriting git history

[dave-doty]

The repo is very large, over 600 MB currently. I think part of that is due to early experiments with pyodide, which involved very large files. I don't recall when they were introduced or removed, but this commit references them: https://github.com/UC-Davis-molecular-computing/scadnano/commit/a5e1f405011265f9e7bee1a747758ff164d58d73

There are ways to rewrite the git history to shrink the repo:

https://www.atlassian.com/git/tutorials/rewriting-history https://medium.com/@sangeethkumar.tvm.kpm/cleaning-up-a-git-repo-for-reducing-the-repository-size-d11fa496ba48

Let's do this so that cloning the repo doesn't take so much data. I'm not sure the best way to go about it.

Update: There's also this option under "How to prune your repos":

https://www.perforce.com/blog/vcs/git-beyond-basics-using-shallow-clones

Before doing this, we can add to the CONTRIBUTING document that to reduce the local repo size, one can use

git clone -–depth [depth] https://github.com/UC-Davis-molecular-computing/scadnano.git

for some value of depth, not sure what.