* enhances visualization of editable column on tables
* simplifies code
* enhances visualization of parcel_group column on tables
* WIP: Ordering on intervention table is odd. Same results are being displayed on page 2. Needs further analysis and fixing!
* disables ordering of parcel_group ("Gemarkung") column on tables
* ordering can not be done properly due to more complex nature of this column's content
* introduces "Keine Geometrie vorhanden" message instead of hour glass icon on entries where no geometry has been entered yet
* properly orders last_modified column by moving null values to the lower end of the ordering
