#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/object.py

@@ -652,10 +652,21 @@ class GeoReferencedMixin(models.Model):
         Returns:
             parcels (Iterable): An empty list or a Queryset
         """
+        result = []
         if self.geometry is not None:
-            return self.geometry.get_underlying_parcels()
-        else:
-            return []
+            result = self.geometry.get_underlying_parcels()
+        return result
+
+    def count_underlying_parcels(self):
+        """ Getter for number of underlying parcels
+
+        Returns:
+
+        """
+        result = 0
+        if self.geometry is not None:
+            result = self.geometry.count_underlying_parcels()
+        return result
 
     def set_geometry_conflict_message(self, request: HttpRequest):
         if self.geometry is None: