#3: added unique constraint to controlled vocabularies; added foreign keys (controlled vocabularies) to models

#3,#4: nested uploads/downloads using controlled vocabulary; still to investigate: how to load enum_tables at beginning (this commit is a workaround)

#4: defined association tables also in models; now using one base for the whole app 'toardb'; this has now also to be adapted to test_base

#1: pytest for data established; renamed date_time to datetime; needed 'no_autoflush' in timeseries queries

adapted sphinx documentation to new structure (ONE app); some pretty printing (fastAPI does not provide sphinx extensions like django)

created ONE toardb app, also adapted pytests for toardb app (still very last test will throw an error for teardown; inserted example for url percent encoding