Add `location` param and support geo search with map on main page

See:

https://github.com/hbz/lobid/issues/88
https://github.com/hbz/nwbib/issues/82
Tweak display of currently selected location

Explicitly state that results are about places in the selected area
and separate it visually from the facets, which behave differently.

Also add 'Kreis' only if it is not part of the name.
Fix regression causing subject chain permutations to be displayed