Removing use of the router for defining superevent list and
detail URLs, so that all of the possible URL/method combinations
are explicitly defined.

Since we use the preferred event to construct much of the VOEvent
for a superevent, we have to select the event's subclass (note that this
is done for events by the event_and_auth_required decorator, which calls
Event.getByGraceid).  This was preventing certain subclass-specific
attributes from being added to the VOEvents, like ProbHasNS,
ProbHasRemnant, etc.

Superevent now always have a letter suffix - remove the logic
which gives the first superevent on a date no letter suffix and
allows it to be looked up without the letter suffix even after
it receives one.

Changing SupereventID -> GraceID and SupereventPage -> EventPage
for consistency with old VOEvents.

Update alert code to determine whether the message should go to
the production, test, or mdc superevent nodes.

Superevent categories are now exposed by the API root, for
use in gracedb-client.

Superevent category is now queryable.  Also set default queries
to not return Test or MDC superevents.

Updated superevent creation and update serializers to handle
superevent categories.  Also updated utils to accept the category
argument and do some checks.

Created ChoiceDisplayField - same as ChoiceField, except its
to_representation() used the display value instead of the key.

Adding utils to Superevent and Event models for comparing
categories and deciding if an Event is the correct category to be
part of a superevent.

Superevents can now be of type 'Production', 'Test',' or 'MDC'.

Models which inherit from AutoIncrementModel can now specify
more than one constraint.  Needed for superevent categories.

Link to correct file versions in superevent log comments

Fixing issue where users could cause superevent date ID lookup
to fail by providing date strings which couldn't be parsed by
datetime.datetime.strptime (ex: '181309', month=13). Now we raise
a custom exception in the class method and catch it in
get_superevent_by_date_id_or_404.

Replacing redundant logic for superevent queries to just use
Superevent.get_filter_kwargs_for_date_id_lookup so as to "NRY".

Fixing ambiguity in superevent date IDs due to use of a 2 digit year.
datetime uses some range like 1969-2068, but we would prefer something
more GPS-centric, so we force it to be 1980-2079.

This will need to be dealt with in advance of 2080, probably
will need to convert to 4 digit years.  Shouldn't be too hard,
will likely need to just make the switch, but maintain legacy
compatibility with legacy URLs, search features, and a check in
Superevent.get_filter_kwargs_for_date_id_lookup, which
points to superevents between 1980-2079 if a 2 digit year is given.

A few divs were inside of the wrong {% endif %} block in the coinc
inspiral templates.  Caused display issues if for some reason the
event did not have any single inspiral events.

Adding serialized label object to label creation and removal
alerts.  This may not be permanent, but some users want this
feature since the object contains a 'self' link which
they use to tell alerts from different servers apart.

Adding DQOK, PASTRO_READY, EMBRIGHT_READY, SKYMAP_READY,
GCN_PRELIM_SENT labels in advance of first OPA test.

Applying SafeCreateMixin to the superevent viewset.  This way,
model-level validation errors will be caught and handled
appropriately.

Adding file url to serialized superevent logs. This matches the
format for event logs and is necessary to display images properly
in the nasty javascript for the web view.

A list of superevents which need operator signoff will appear
on the home page if the user signs in from an IFO control room.

Adding some optimization in search forms by using select_related
and prefetch_related.  Some of this is on the Superevent model
within the get_internal_events and get_external_events methods.

Show group, pipeline, search by default for event searches,
hide link to files.

New /latest/ page includes events and superevents. We also
move the old events 'latest' page to /events/latest/, changed the
view name, and fixed reverses to that page appropriately.

Adding view functions, templates, and full nasty javascript
to get a more complete and (hopefully) temporary implementation
of the superevent detail view ready. This includes buttons for
allowing/removing LV-EM access and forms for signoffs.