* Membership updater refactoring
* Pass in membership state
* Use membership check rather than referring to state directly
* Delete irrelevant membership states
* We don't need the leave event after all
* Tweaks
* Put a log entry in that I might stand a chance of finding
* Be less panicky
* Tweak invite handling
* Don't freak if we can't find the event NID
* Use event NID from `types.Event`
* Clean up
* Better invite handling
* Placate the almighty linter
* Blacklist a Sytest which is otherwise fine under Complement for reasons I don't understand
* Fix the sytest after all (thanks @S7evinK for the spot)