SmartSearch tuning

acdhOeaw\arche\lib\SmartSearch major rewrite of the search() method:

• Search code split into smaller and easier to manage chunks.
• Named entities linking is now done separately for the FTS and the spatial search with results being joined only afterwords. This allows independent named entity links to FTS and spatial matches.
• Spatial search extracts geometry to make it easy to narrow down the map facet values to the ones matching the search.
• The search() method returns false on an empty search and true otherwise.