Support linking multiple concepts to the map

[Aklakan]

This would enable one to create overlays of different concepts.
A color attribute would then be needed as well.
Also, once this works, show a list of active MapLinks.

(MapLink is the property path that relates the faceted-search-concept to the geo-concept).

This depends on Issue #4

[Aklakan]

Removed Conti label - for this we need to significantly revise the workspace system.

[Aklakan]

(Accidental close)