Allow display of non-NWBib resources and link to them (#45)

- Don't add the `set` filter for direct access by ID
- Change `isPartOf` links to stay in the NWBib UI
- Move `isPartOf` field in details view below `Quelle`
Display proper message on direct access using non-existing ID
Improve items table in and below map (#68)

- Always add table below map (independent of number of markers)
- Always add owner and signature rows (even if details are missing)

Samples with issues fixed by this: BT000168958, HT014286353