Also squash migrations in the alerts app.

superevent_id is now always default superevent ID (SXXXXXXa),
while a new 'gw_id' field is either None or the GW ID.
We also add the 'far' field which is just the preferred event's FAR.
Finally, we remove some fields for unauthenticated users.

We now have a single API endpoint, /api/, which can handle all
authentication methods directed to it.  The /apibasic/ and
/apiweb/ URLs will probably be maintained for legacy reasons,
but will not include any additional logic (they will just be
carbon-copies of /api/ under a different namespace).

Some of the search utilities were still in the separate
events and superevents apps, so we moved them to the search app
and tried to clean things up a bit.  It's still kind of a mess
and probably not worth doing a full cleanup until we rework
the search.

RobotUser should only be used for robot user accounts.  It's a clunky
way of identifying robot accounts, but it's all we have for now.

All calls to event.graceid() -> event.graceid.

* Consolidated *all* of the search stuff into the search app
  (previously the flexigrid stuff was in events/superevents)
* Completely removed the old events-only search and latest views,
  templates, etc.
* Removed some old unit tests which tested the events-only search

User documentation updated to include information about new
LVAlert contents and show serialized event, superevent, and
annotation objects.  Also an overall update of any missing or
outdated information.

Renaming LIB -> oLIB and gstlal-spiir -> spiir, at the request of
the pipelines.

Missed one case where 'tag' should have been 'tags' in
58efeab3. Also updated same thing
in documentation.