SHOW MOMENTS
Display the 4 "moments" images derived from a datacube by command MO-
MENTS. The contour spacing for each image is controlled by its own
variable:
AREA_SPACING for the integrated area M_AREA
PEAK_SPACING for the peak brightness value M_PEAK (in K)
VELO_SPACING for the Velocity field M_VELO (in km/s)
WIDTH_SPACING for the Width field M_WIDTH (in km/s)
As for other image displays, CENTER and SIZE control the center and size
of the image (in arcsec).