-merging polygon vertices that are judged to be extremely close together to reduce numerical complications with polygon surface area calculations [function name: filter_polygon_vertex_coordinates_for_extreme_proximity() ]
-simplified the unit test that uses randomly-placed generators on the unit sphere + calculates surface area (filtering to remove generators that are extremely close)
-similarly for the matching unit test with 'regularly-spaced' generators
-unfortunately, the reconstituted surface areas don't seem to have been improved by very much, if at all, but this may alleviate the generation of improper test Voronoi diagrams given practically coincident generator vertices