* change get_restricted_data and get_projector_data to always use a list
* Add typings to all get_restricted_data and get_projector_data methods
* Replace CollectionElementList with a real list
* Fixed arguments of inform_deleted_data
* Moved CollectionElementCache to cache.py and refactored it
* Run tests with cache enabled (using fakeredis)
* Second websocket channel for the projector
* Removed use of projector requirements for REST API requests.
Refactored data serializing for projector websocket connection.
* Refactor the way that the projector autoupdate get its data.
* Fixed missing assignment slide title for hidden items.
* Release all items for item list slide and list of speakers slide. Fixed error with motion workflow.
* Created CollectionElement class which helps to handle autoupdate.
- Used raw SQL for createing default projector during inital migration.
- Removed default_password and hidden agenda items from autoupdate data for some users.
- Removed old get_collection_and_id_from_url() function.
