Implement our own history for the message composer
It would allow us to have one history per room. It would allow us, among other things, to be able to start composing a message, then switching room, then coming back and get the message back where we started.
It should also fix a regression introduced in !1119 (merged) where the undo/redo of the composer ignores Pills, which is a weird behavior.
Edited by Kévin Commaille