This adds extensive API documentation based on the official API
documentation [1] and conflict resolution [2] documents.

Where possible field documentation was added to models or serializers,
so that other code like auto-generated forms can also profit from these
changes (hence the migration part of this commit).

The changes introduce two new API endpoints.

`/api/v1/schema/` exposes the API schema as an OpenAPI 3.0.3 document.
The standard format is yaml but can be switched to JSON by appending the
`?format=json` query parameter.

`/api/v1/schema/swagger-ui/` renders a visual representation of the
OpenAPI 3 specification with support for testing the individual API
endpoints including authentication.

[1]
https://gitlab.servus.at/aura/meta/-/blob/ec3c753d34ccb0269969808ac7dc28fff2ff1648/docs/development/api-definition.md
[2]
https://gitlab.servus.at/aura/meta/-/blob/ec3c753d34ccb0269969808ac7dc28fff2ff1648/docs/development/conflict-resolution.md

This adds extensive API documentation based on the official API
documentation [1] and conflict resolution [2] documents.

Where possible field documentation was added to models or serializers,
so that other code like auto-generated forms can also profit from these
changes (hence the migration part of this commit).

The changes introduce two new API endpoints.

`/api/v1/schema/` exposes the API schema as an OpenAPI 3.0.3 document.
The standard format is yaml but can be switched to JSON by appending the
`?format=json` query parameter.

`/api/v1/schema/swagger-ui/` renders a visual representation of the
OpenAPI 3 specification with support for testing the individual API
endpoints including authentication.

[1]
https://gitlab.servus.at/aura/meta/-/blob/ec3c753d34ccb0269969808ac7dc28fff2ff1648/docs/development/api-definition.md
[2]
https://gitlab.servus.at/aura/meta/-/blob/ec3c753d34ccb0269969808ac7dc28fff2ff1648/docs/development/conflict-resolution.md

- update the model
- migrate the model
- update the serializer
- update the views

- updated the fixture
- updated the serializer
- updated some views

Close #52

Added requirements and installation instructions for using PostgreSQL and apparently there were another migration necessary.

* for adding a number of (business) days to the schedule (e.g. "on the rrules' following day")
* fixed a bug for monthly recurrences
* and some minor changes

See #8

* added corsheaders middleware to work properly
* fixed bug when updating a timeslot
* after updating a timeslot, its repetition will be returned if there's one
* included field 'ppoi' in shows

See #22 #23

See #21 #23

and:
* Set correct login redirect url for oidc
* Added django-cors-headers for cross-domain api requests

See #21 #22

...and filters for admin ui and api.

See #21

Changed note filters:
- ?owner=1 returns all notes a user may edit
- ?user=1 returns all notes a user created

See #22

* Users can see and change all notes and hosts of shows they own - even if they were created by another show owner
* A host can be assigned to a note (if host is editable)
* Added django-oidc-provider app
* Added limit/offset pagination to endpoints /shows, /timeslots and /notes
* Common users may not change the show's name anymore via API
* Playout API can be called with start (date) and end (date) parameters
* Added filters to endpoints:

/shows/?host=1  Retrieves shows of a given host
/shows/?owner=1 Retrieves shows of a given owner (= user ID)
/notes/?host=1  Retrieves notes assigned to a host
/notes/?owner=1 Retrieves notes a user has created (= user ID)

Had to set settings const USE_TZ (= reflect timezone in mysql datetimes) to True for OIDC to work with mysql.

Don't know yet if that's a problem.

See #22 #23

See #21

Shall we still put this in a sub app?
Would still need to figure out how to hook from the sub app into the serializer viewsets (and not vice versa) in order the custom fields get saved.

See #21