* Added support for message send checkpoints (as HTTP requests, similar to the bridge state reporting system) by sumnerevans.
* Added support for aiosqlite with the same interface as asyncpg.
* This includes some minor breaking changes to the asyncpg interface.
* Made config writing atomic (using a tempfile) to prevent the config disappearing when disk is full.
* Changed prometheus to start before rest of `startup_actions` (thanks to Half-Shot in 63).
* Stopped reporting `STARTING` bridge state on startup by sumnerevans.