#160 Parcel number to parcel table

* adds number of all underlying parcels into parcel table
* reworks minor code parts of parcel related logic
* fixes bug where under certain circumstances a parcel would have been added twice to a geometry
* removes unused parcel fetching on intervention detail view

konova/models/geometry.py

@@ -152,6 +152,7 @@ class Geometry(BaseResource):
             underlying_parcels.append(parcel_obj)
 
         # Update the linked parcels
+        self.parcels.clear()
         self.parcels.set(underlying_parcels)
 
         # Set the calculated_on intermediate field, so this related data will be found on lookups
@@ -172,7 +173,6 @@ class Geometry(BaseResource):
         Returns:
             parcels (QuerySet): The related parcels as queryset
         """
-
         parcels = self.parcels.filter(
             parcelintersection__calculated_on__isnull=False,
         ).prefetch_related(
@@ -184,6 +184,17 @@ class Geometry(BaseResource):
 
         return parcels
 
+    def count_underlying_parcels(self):
+        """ Getter for number of underlying parcels
+
+        Returns:
+
+        """
+        num_parcels = self.parcels.filter(
+            parcelintersection__calculated_on__isnull=False,
+        ).count()
+        return num_parcels
+
 
 class GeometryConflict(UuidModel):
     """