This reverts commit 77bfa13b.

feat: use Django model permissions for Category, FundingCategory, Language, License, LinkType, MusicFocus, Topic annd Type

This apparently needs to done in a separate migration step

Closes: #185

Closes: #178

Closes: 183

remove TimeSlotManager and use them as functions

Closes: #180

This reverts commit 3c611393.

The filter annotation for ordering by show ownership introduced
a join that caused some results to appear more than once.

The dashboard will need to implement a paginated list of shows
that should be searchable.

The dashboard must be able to sort shows.

In aa7e7f41 filters were renamed
to a camelCase scheme. This is actually wrong, because the filter
names are already transformed to snake_case when the are applied
to the FilterSet.