As the TCP replication uses a slightly different API and streams than
the HTTP replication.

This breaks HTTP replication.

This timestamp is used to indicate when the user last sync'd

The TCP replication protocol streams deltas of who has started or
stopped syncing. This is different from the HTTP API which periodically
sends the full list of users who are syncing. This commit adds support
for the new TCP style of sending deltas.

This defines the low level TCP replication protocol

The new replication protocol will keep all the streams separate, rather
than muxing multiple streams into one.

Fix bug where current_state_events renamed to current_state_ids

* Bail early if remote wouldn't be retried

* Don't always return true

* Just use get_retry_limiter

* Spelling

Don't user upsert to persist new one time keys

Notify on new federation traffic

Fix installation issues

Batch sending of device list pokes

Short circuit if all new events have same state group