The canonical way of displaying lists in Qt is via models.
Thus, return the tripId directly from the DiveListModel instead
of going indirectly via a DiveObjectHelper. In the future, this
will allow us to make the DiveObjectHelper value-based, as it
is not generated numerous times for every list item.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
1b9581369a