Symbolicmode

This is the same source as 2.0.0, but with 3.12 marked in the support matrix.

I had picked the CLI semantics for chmod(mode, path), and feel that was a mistake, so I switch it to match os.chmod(path, mode). I wanted to make this change while it's still fairly early in the library's life, before too many people were using it.

BREAKING CHANGE: chmod() arguments are changed to match os.chmod

Michael Still submitted a patch that changes the allowed versions from 3.7+ to 3.6+, and tests passed on my Python 3.6 box (Ubuntu 18.04, Michael points out RHEL 8 has 3.6 as well). Thanks for the patch Michael.

This version has undergone hours of fuzz testing comparing against system chmod, plus code review, and I'm pretty happy with the structure of the code. So I'm ready to call this version 1.0 and start considering this stable.

This is just some clean up to try to make the code read easier. Logic is the same, tests pass and extensive fuzzing run, just trying to remove some repetition and make the code read better.

This is the same as version 0.9.1, but I did a bunch of test releases trying to hammer out some things in github workflows and so I wanted to release a new version that is larger than all those test versions just so there wasn't any confusion.