Computes a contour list from the given input object.
      The input object is read from stdin and output data are written
      to stdout unless filenames are given.
      Example: WlzContourObj -i -v 0.0 in.wlz
      The input Woolz object is read from in.wlz, and the iso-value
      (iso-value = 1.0) contour list is written to stdout.