* 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
* improves frontend layout to display more details on district, municipal and parce group
* improves ordering of parcels
* refactors parcel related models
* improves parcel fetching
* extends and simplifies sanitize_db parcel related code
* adds support for POST of new compensations
* adds shared_users property to BaseObject and Compensation to simplify fetching of shared users (Compensation inherits from intervention)
* extends compensation admin index
* modifies compensation manager which led to invisibility of deleted entries in the admin backend
* fixes bug in sanitize_db.py where CREATED useractions would be removed if they are not found on any log but still are used on the .created attribute of the objects
* extends sanitize db command to remove unrelated parcels and district from the database
* fixes bug where single parcel wfs match would lead to unexpected behaviour
* adds admin interface for parcels and districts
* adds updating of parcels in case of SimpleGeomForm saving
* refactors geometry field into GeoReferencedMixin, holding more handy methods and used in all models, formerly holding the geometry field
* refactors backend admin configuration, so modified, deleted and created are not editable in the backend which also skips loading of all possible choices
* fixes typo in sanitize_db command
* introduces GeometryConflict model, holding a link between two geometries, where one overlaps the other
* adds first (WIP) messages into detail views of ema and intervention for test purposes
