DropGeometryTable should not raise exception if no geometry column

[aperi2007]

Actually the DropGeometryTable? raise an exception if the table has no geometry column.

This patch avoid this exception. So the DropGeometryTable?() drop always the table if there isn't object dependent from it.

[aperi2007]

Patch to avoid exception if no geometry column

[aperi2007]

Hi, this patch for avoid the exception to DropGeometryTable?() is ok ?

[strk]

r7014, includes testcase