-3d / -3dii + RAXIS bug

Thanks to a bug report a corner case has been identified, between the use of the 3d or 3dii pipeline and RAXIS (general Rigaku?) detectors. in XDSIndexer and XDSIndexerII I compute the low resolution limit from the spot list. For Rigaku detectors however distance is defined to be negative, which causes problems. Adding this small fix:

        if distance < 0.0:
            distance *= -1

After

        distance = values[14]

Will however fix the problem (I think!)