io.segwizard: multiple changes

    - added support for reading simple SegmentLists
    - added write support for DataQualityFlags
    - removed duplicate of segmentsUtils reader
io.ligolw.segments: added DataQualityFlag writer

    - writes DataQualityFlag to LIGO_LW with Segment, SegmentSum and SegmentDefTables
segments.DataQualityFlag: added write methods

    - removed non-implemented LIGO_LW methods
    - added write to io_registry, works for 'segwizard' and 'ligolw' format