Improve naming consistency

This has the following known shortcomings:
 - It doesn't handle missing events not in the from/to range.
 - It doesn't order events in the timeline correctly.
 - It doesn't handle invited/left rooms at all.
 - There is no intelligent wakeup logic: events for Bob will wake up Alice's stream.

Also ensure every sync response has a `next_batch` token by forcing
it in the constructor, as previously timeouts would not have a token.

Currently the HTTP handlers are attached to an API mux which is created inside
Setup(). In the future, we'll want to split this out so a single mux can have
both sync and clientapi handlers attached to it.

This distinguishes them from tools like 'kafka-producer'
which are not required to run a dendrite server.

The prefix also groups together the dendrite binaries nicely
on `ls` as well as making it nicer to tab-complete.

* Update gomatrixserverib dep

* Use helper functions when creating rooms

* Use gomatrixserverlib.StateKeyTuple

* Add option to stop processing input after a given number of messages

* Implement state conflict resolution

This involves:
 - Parsing the HTTP request
 - Requesting auth events from the roomserver via the Query API
 - Building the event
 - Doing auth checks on the event
 - Sending it to the roomserver input log