Added test<7>() for the poorly reported bug ticket #610 - bug not reproducible.

git-svn-id: http://svn.osgeo.org/geos/trunk@3740 5242fede-7e19-0410-aef8-94bd7d2200fb
Fix GEOSPointOnSurface with zero-length linestring (#609)

git-svn-id: http://svn.osgeo.org/geos/trunk@3741 5242fede-7e19-0410-aef8-94bd7d2200fb