mlecoeuvre/H2GIS — pull request #2 by agouge (2014-01-27 13:30:36+00:00)
Title: Add missing signature and examples.

`ST_Extent` is an aggregate function, so you need to have at least one aggregate example. Can you add an illustration for this example?

Note the last example I added returns a `POINT`.

I also added a missing signature.