* fixes minor bug where invalid geometry (self intersecting) could not be used properly as input for WFS parcel intersection calculation
* future enhancements regarding map client will make sure invalid geometries can not be added in the first place
* 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
