Invert the grey-range of a grey-level woolz object
      writing the new object to standard output
      The original grey-values are transformed
      from their original range. The transformation is
      new_grey = u + l - old_grey. where u and l are the upper and lower values of the inversion range. Options are:
      -l#       low grey value, default min value in source
      -u#       upper grey value, default max value in source
      -h       help - prints this usage message
      -v       verbose operation