* Changed wording: element is one element on the projector. A slide is a functoin to render one element
* Use AllData as first argument all the time
* Render username on server
* Add exceptions for erros on projector
* Fix motion recommendation
* Only show state extension, if it is allowed by the state
* Add motion_change_recommendations to motion full_data
* Activate restricted_data_cache on inmemory cache
* Use ElementCache in rest-api get requests
* Get requests on the restapi return 404 when the user has no permission
* Added async function for has_perm and in_some_groups
* changed Cachable.get_restricted_data to be an ansync function
* rewrote required_user_system
* changed default implementation of access_permission.check_permission to
check a given permission or check if anonymous is enabled
* geis does not work with channels2 and never will be (it has to be python now)
* pytest
* rewrote cache system
* use username instead of pk for admin user in tests
