Renaming the `master` branch to `main`

[offbyone]

This weekend I will be renaming our master branch to main. No commits should be lost, but remotes will need to be updated.

[brunns]

Good news! I very much need to do the same on some of my repos.

[brunns]

#154 and #157 might be small enough to merge first. But then, I would say that, wouldn't I? 😉

[offbyone]

Merged those, and the branch is changed.