This change implements a show overview page with two display modes:
table and grid. Shows can be ordered and searched. Other filters are not
(yet) implemented.

refs #101
refs #181

The AddShowButton was not rendered when the shows weren’t loaded, but
the only requirement for it to render should be if the user is a
superuser.

refs #127

This component implements the logic for the standard
django-rest-framework (DRF) order parameter.

DRF uses plan field names for ascending and a "-" prefix for descending
order.

Example:
	if you’d want to sort by id you’d write:
		?order=id
	if you’d want to sort by id in reverse order you’d write:
		?order=-id

The OrderFilter supports arbitrary order fields, allows you to set the
sort direction (ascending, descending – configurable per order field)
and supports re-ordering of order fields so that that hierarchical
orders can be set.

This is a helpful ADialog wrapper that manages it’s open state by
itself.

This is sometimes useful when we don’t want to modify the global page
navigation state, but want to use independent lists.

This should make the API functions more accessible for callers as there
won’t be any loose undefined values that were sometimes needed to skip
certain values in certain API endpoints.

Instead, every positional argument is now required and all configurable
options or extensions are part of the options object.

refs #179

refs #179

Using the ID type makes type errors more likely because we accept a
wider range of types as arguments for API operations than we actually
support on a logic level, i.e. when using maps because

	Map<ID, T>.get('1') !== Map<ID,T>.get(1)

Sometimes we want to query the API for certain objects. We can now do
that by passing a URLSearchParams object to list operations.

All requestInit arguments could have been undefined already, because we
declared it as an optional argument, but sometimes it’s nice to
explicitly skip the argument with `undefined` which is now possible as
well.

Sometimes we don’t have a static list of choices but an async source for
them (like an API endpoint). This is now supported out of the box
through the searchProvider prop.