Add spatial filtering (inCircle, inRectangle)

[sfkeller]

Filtering of geospatial data seems to be an important use case.

OSM is involved here, and Wikidata has the "coordinate location" property (P625).

(BTW: Pls. use this coordinates P625 in Wikidata, don't use property "OSM relation ID" P402).

Blazegraph release 2.1.0 obviously contains support for the processing of points. Points are represented as a dedicated typed literal that encodes geospatial coordinates (lat/lon). Predicate "geo:search" includes "inCircle" and "inRectangle", which extracts all coordinates that are in a within a given radius or bounding box.