Whether test coordinates for geometry - subclass specific code
Implementors can assume that dimensin, type, srid and haveMeasure are
equal, other != null and other is the same subclass.
This is a subclas of PGgeometry that uses hex encoded EWKB to communicate
with the backend, which is much more efficient, but only works with Lwgeom
enabled PostGIS (1.0.0 and up).