#4: nested upload for stations done; TBD: more testing (esp. pytest), use controlled vocabulary (related to #3)

#4: nested download for stationmeta realized; TBD: uploading of new test database, nested download for stationmeta

#8: common base and test base is in place (but teardown of test_base has to be worked on for chained pytests)

#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

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