Returns a string stating if a geom is valid or a reason why if it
Optional variable selfTouchValid sets whether polygons using
self-touching rings to form holes are reported as valid. If this
flag is set, the following self-touching conditions are treated as
The shell ring self-touches to create a hole touching the shell
A hole ring self-touches to create two holes touching at a point
The default of 0 (following the OGC SFS standard) is that this
condition is not valid. Set it to 1 to consider it valid (c.f.
ESRI SDE model).