added support for generic grids

src/Zonstat.c

@@ -104,9 +104,10 @@ void *Zonstat(void *argument)
 
   index = 0;
   gridID1 = vlistGrid(vlistID1, index);
+
   if ( gridInqType(gridID1) != GRID_LONLAT &&
        gridInqType(gridID1) != GRID_GAUSSIAN &&
-       !(gridInqType(gridID1) == GRID_GENERIC && gridInqYsize(gridID1) <= 1) )
+       !(gridInqType(gridID1) == GRID_GENERIC && gridInqYsize(gridID1) > 1) )
     cdoAbort("Unsupported gridtype: %s", gridNamePtr(gridInqType(gridID1)));
 
   gridID2 = gridToZonal(gridID1);