The event url now contains the date and day (group) instead of just the date.
Requests that only contain a date are redirected if there is only one day
(group) that has an event on this day, otherwise an error is returned.

This updates to rocket 0.4 and handles all the breaking changes. However,
there are several new features and improvements that are not used.

This does not yet use all features of the new edition.

This deletes all data from the database on startup. It can be used to setup
a demo system, that is regularly restarted to keep the database clean.

This removes all associated data of the year, including the audit log.

The tutors and ip_whitelist tables were missing foreign keys for their
year columns.

Nginx supports proper caching.

Previously the name of a student was stored as a single string. Even though
this is the correct way, it complicates the import and sorting, because the
original data source (almaweb) also stores the names separated. Before this
change, the name parts were concatenated before import, which is obviously
wrong. After this change, the names are imported and exported untransformed.

To still support the correct workflow and also cultures which do not fit into
this name schema, the family name is optional. The migration also just moves
the complete name into the given name field.

The display of the names is still incorrect in most of the tutor facing
views, as given and family name are still concatenated. However, the admin
view and export are now correct.

This is no longer needed, as we now support a proper csv export, both
for the examnimation office and a complete export.

The exports contains all participants of the selected year and a column
which determines if the student has passed the course.

The whitelist is disabled by default and does not affect site admins. It
can be configured through the admin interface.

It uses the postgresql inet support for storing hosts and nets and for
figuring out, if a host is part of a net. This works for both IPv4 and
IPv6.

This uses the hyper-sse crate to run a push server on a separate thread,
because Rocket does not support SSE yet.

Currently only changes to tasks, elaborations and comments are pushed,
but this can be easily extended. The year is used as a push channel
identifier, because it is the privilege boundary for tutors and is
complete in the sense that there is no page that displays specific
information that needs push messages from more than one year.

Alternatively, a set of groups could be used as a channel identifier.
This would theoretically result in less transferred messages, but as
all tutors are looking at the same or similar pages during a single
event of the hardware course, it would not make much practical
difference.

This is redundant and not strictly necessary, as all groups are children
of an experiment element that also contains this id, but it allows
selecting a specific group/experiement combination in the same way as
on the group overview page, and so makes the upcoming javascript push
implementation easier.

The service worker is empty for now, so there is no offline of caching
functionality.

Displays a compact overview of the progress of the groups in a event.
It is only activatable by a secret keyboard shortcut for now: CTRL+#