commander>Centered Grid
   comment>** Set up the grid for Rotate and or Perspective Transform
   comment>*    Set values from python-fu image object
   >>>centerX = theImage.width/2
   >>>centerY = theImage.height/2
   >>>gridSpacing = max(theImage.width, theImage.height)/24
   comment>*    configure grid with PDB functions
   >>>pdb.gimp_image_grid_set_offset(theImage, centerX, centerY)
   >>>pdb.gimp_image_grid_set_spacing(theImage, gridSpacing, gridSpacing)
   >>>pdb.gimp_image_grid_set_style(theImage, GRID_ON_OFF_DASH)