Support saved-state syncing
Because of how matrix works, when the bot connects to the server it syncs the whole history each time. The library we're using supports keeping track of state locally then only syncing what's changed from the local version. This could help speed up bot boot times if we were to support this.
Note at the moment this is low priority because the bot is fairly fast to start and sync, when adding the bot to larger rooms (ie, general) could be an issue.