* `_auth_and_persist_outliers`: mark persisted events as outliers
Mark any events that get persisted via `_auth_and_persist_outliers` as, well,
outliers.
Currently this will be a no-op as everything will already be flagged as an
outlier, but I'm going to change that.
* `process_remote_join`: stop flagging as outlier
The events are now flagged as outliers later on, by `_auth_and_persist_outliers`.
* `send_join`: remove `outlier=True`
The events created here are returned in the result of `send_join` to
`FederationHandler.do_invite_join`. From there they are passed into
`FederationEventHandler.process_remote_join`, which passes them to
`_auth_and_persist_outliers`... which sets the `outlier` flag.
* `get_event_auth`: remove `outlier=True`
stop flagging the events returned by `get_event_auth` as outliers. This method
is only called by `_get_remote_auth_chain_for_event`, which passes the results
into `_auth_and_persist_outliers`, which will flag them as outliers.
* `_get_remote_auth_chain_for_event`: remove `outlier=True`
we pass all the events into `_auth_and_persist_outliers`, which will now flag
the events as outliers.
* `_check_sigs_and_hash_and_fetch`: remove unused `outlier` parameter
This param is now never set to True, so we can remove it.
* `_check_sigs_and_hash_and_fetch_one`: remove unused `outlier` param
This is no longer set anywhere, so we can remove it.
* `get_pdu`: remove unused `outlier` parameter
... and chase it down into `get_pdu_from_destination_raw`.
* `event_from_pdu_json`: remove redundant `outlier` param
This is never set to `True`, so can be removed.
* changelog
* update docstring
Richard van der Hoff