Based on current master + clikt 1.7.0

This is a squash merge of `complete-revision`.

Parts of the changes are heavily inspired by GNOME Lollypop.

Modules can't contain slashes and class names seem to follow CamelCase
style.

That's a binary prebuilt by me. Later, we should build it by source.

I would like to use v11 as v10 is already deprecated, but it fails when
building with that newer version.

Source:
https://code.briarproject.org/grote/briar-cli-python-demo/blob/8ced7b9f37e6ee59dac6042c9bcf21c54c648e9e/briar-cli.py

Based on a template generate by Gnome Builder.