* Fix #684
* Fix #683
* Add `CHANSERV CLEAR`
* Allow mode changes from channel founders even when they aren't joined
* Operators with the chanreg capability are exempt from max-channels-per-account
* Small fixes and cleanup
This moves channel registration to an eventual consistency model,
where the in-memory datastructures (Channel and ChannelManager)
are the exclusive source of truth, and updates to them get persisted
asynchronously to the DB.
Add very initial ChanServ and NickServ virtual clients
As well, add channel registration and re-applying founder privs on the first client joining the channel. I'm going to re-architect our modes system to better acocunt for this sort of change.