Open source composition of Edition 3

Progress on the third edition is likely to go much faster if everyone is able to contribute. Although I’ve heard that work on the third edition is indeed in progress, there’s so far nothing visible (yet) — a “work-in-progress” branch of the repository where pre-release contribution to the third edition would be possible would at least get more contributors on board, and the more possible contributors, the faster the development of the third edition of the book would go.