* Add API for querying events by ID.

* Fix tense

* Start implementing federation ingress

* More stuff

* Hook up federation event receiving

* Handle the case where we are missing state

* Fix docstring and comments

* Fix infinite loop when printing unknownRoomError

* Return the requested portions of current state in the query API

* Use Unique from github.com/matrix-org/util

* rewrite bulkSelectFilteredStateBlockEntries to use append for clarity

* Add test for stateKeyTupleSorter

* Replace current with a new StateEntryList rather than individually setting the fields

This should:
    1) Make the input package a bit cleaner.
    2) Allow use to reuse the state reading code from the query package.

* Add method for calculating the room state after a list of events

* Fill out AddsState and RemovesState fields in the output event

* comment on return value

* Fix whitespace

* Clarify the meaning of LastEventIDSent

* Be more explicit on what the snapshot is

* Fix comments

* Comment on why we want the state after the previous events

* 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