improve assertion on scheduling test
Correctly order timeslots
Extract add_timeslot_order into separate file
Removing TODOs that are done or that don't look valuable
Garbage el exists, but doesn't do anything
Unscheduling classes remove them from matrix, directory, datastructure
Schedule assignments persist through reload

* unschedules do not
* errors don't get reported
* no tests
Separate API client and tests around using the api client