* 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

* Get the SQL working, and make it more idempotent

* 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.

Terse function names are used to make usage not stutter. For example:

```go
err := error.Forbidden("you shall not pass")
```

At the moment they are all the same fundamental `MatrixError` type. This will
be bad if we ever want to `switch` based on the kind of error. I'm hoping we
won't ever need to introspect into errors like this: ideally these errors would
be created purely for immediately being returned in an HTTP response.

`MatrixError` implements the `error` interface.

* Add basic routing based on matched paths
* Make /sync and /send use the right API paths

* Move partition offsets sql to a separate file

* Move event types sql to a separate file

* Move event state key sql to a separate file

* Move room sql to a separate file

* Move events sql to a separate file

* Move event json sql to a separate file

* Move state snapshot sql to a separate file

* Move state block sql to a separate file

* 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

Add stub clientapi webserver with readers/writers packages

As per RL discussion with Mjark

* A kafkaesque room event consumer for the roomserver.

Implement the main input loop for the roomserver.

It will receive events from a kafkaesque event source and track
where it is in the stream.

It currently does nothing with the events it consumes.