Add a commit-msg hook lint and various other cleanups

Turns out that gitlint by default enforces the exact commit-msg format that I
like to use. I'm enabling this because even I write poor commit messages
sometimes, and looking back on my commits from even a few days ago is sometimes
not very helpful.

I also made some minor comment and nix changes that I noticed while reviewing my
work from the last few days.

0 files changed, 0 insertions, 0 deletions