git-alltrees: root trees and subtrees without duplicate commits.

Hi all,

For a very quick introduction, I'm a career physicist. I just thought
I'd share a detailed method and implementation I developed to improve
on shortcomings of subtrees.

This says it all
https://gitlab.com/douglas.s.leonard/alltrees/-/wikis/home

But to repeat a little...

First, it allows a container "sub" tree, ie syncing only the non "sub"
parts of the tree to a repo.  But maybe more importantly, when it
pulls from the trees it's able to "remap" or reconstruct old commits
back to their originals to avoid the duplicate commit issue of
subtrees.  This is round-trip reproducible so consistency is kept both
ways. It avoids the need for squash with subtrees. Compare the two
images in the wiki to see the difference between subtree without
squash and alltrees. Non-FF changes made in a tree repo show as
branched and merged. Traditional advantages of subtrees are kept,
primarily that users/developers of any one repo don't need any
awareness of how to use the subtrees or the other repos.

I have used this some, but not extensively yet.  In my use it has
worked.  I think it's pretty quick, but I haven't tested on large
projects.

Cheers,
Doug Leonard