spgist 2d bindings for geometry

[robe]

Before I forget -- didn't see it on the list, and Paul you said you have it planned for 2.1.

spgist is a new gist type supported in 9.2. We will start with just 2d support for 2.1 and perhaps later nd.

Creating an spgist index would look like:

CREATE INDEX idx_edges_geom_spgist ON edges USING spgist (geom);

Details on spgist:  http://www.pgcon.org/2011/schedule/events/309.en.html