Forward the MUIA_Listview_DragType and MUIA_Listview_DefClickColumn
attributes to the list object in OM_NEW and OM_GET (they were already
indirectly forwarded by the Group superclass for OM_GET, but that's less
efficient and could be considered a side effect or lucky accident. However,
this is the way OM_SET works currently - there is no OM_SET in Listview - so
maybe there is no need for an OM_GET either).
git-svn-id: https://svn.aros.org/svn/aros/trunk/AROS@52952 fb15a70f-31f2-0310-bbcc-cdcc74a49acc