* refactors WFS fetching to proper POST handling
* adds authentication support to WFS handling
* reduces dummy geometry for tests to a small area to reduce test network traffic overhead
* fixes bug in GeometryConflict conflict checking
* WIP: introduces new konova/utils/wfs/spatial holding SpatialWFSFetcher, which can be fed any geometry and it returns found features
* WIP: adds tests for wfs fetching
* updates requirements.txt
* removes unused messages
* adds geometry conflict message rendering for KOM and OEK
* removes unused methods in GeoReferencedMixin
* generalizes geometrical lookup for conflicts from overlaps to intersects
* 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
* changes the autocomplete route for user retrieving from _istartswith to full qualified check
* extends the help text for form to inform about full qualified username needed
* updates translation
* adds file mime type check on NewDocumentForm
* adds file size check on NewDocumentForm
* adds is_xy_valid methods as classmethods on AbstractDocument
* adds translations for error messages
* updates help text on NewDocumentForm file field
* moves updating of shared access users into ShareableObjectMixin
* renames ShareInterventionModalForm to ShareModalForm since it's used for EMA and eco accounts as well
* renames model ResponsibilityData into Responsibility
* renames model LegalData into Legal
* moves form->object saving logic into model
* refactors NewDocumentForm into special types for intervention, compensation, eco account and ema
*
* implements 5) "Add 'Maßnahmentyp' for KOMs "
* prepares model and form fields as mixins for easy extension to eco accounts and emas (possibly in the future?)
