* Track which events have been sent and the last event sent for each room

* Write output events

* comment that an event could be sent twice

* Marshal and Unmarshal methods for roomserver input api

* Comments for why we don't json.marshal the InputRoomEvent directly

* More comments

* s/m.room.create/the first event/

* Track which events are the latest events in the room.

* Calculate and store the state at each event

* Use type aliases for numeric IDs

* Check that events pass authentication checks.

Record the list of events that the event passes authentication checks
against.

* Storage functions for event types
* Consume outlier room events