* adds another validity check to SimpleGeomForm (is_size_valid) to make sure the area of the entered geometry is somehow rational (>= 1m²)
* optimizes performance of django command sanitize_db
* extends Geometry model with two new attributes, holding timestamps when a parcel calculation has been started and ended
* finally drops unused update_parcel_wfs in favor of update_parcels in Geometry model
* refactors update_parcel method
* adds geometry buffer fallback in schneider/fetcher.py to avoid emptying of geometries when parcels shall be fetched
* finally removes utils/wfs/spatial.py
* extends GeomParcelsView according to #381
* updates translations
* removes redundant psycopg2-binary requirement
* refactors update_parcels() method in Geometry model to work on Schneider
* old WFS based logic still exists as update_parcels_wfs() in Geometry model to have a fallback. Can be deleted in the future
