ref: d13ece698f02288c56cf46f3a20ecc1aaf8004f5
parent: 0058331aeb027f7441a04d99cc7c1e445bd896d9
author: Simon Tatham <anakin@pobox.com>
date: Fri Apr 21 12:19:49 EDT 2023
Generalise the midend serialisation callbacks. These are currently only used for internal serialisation of midend state in order to undo/redo across New Game, and are named accordingly. But I'm about to reuse them for another set of serialisation functions, so they'll want more general names, and also need to be moved higher up in the source file so as to have been defined where I'll want to use them.