Change the signature from of the virtual doFilter() functions from
bool doFilter(struct dive *d, QModelIndex&, QAbstractItemModel*) const;
to
bool LocationFilterModel::doFilter(struct dive *d) const;
as the QModelIndex and QAbstractItemModel parameters were not used.
This makes this functions independent from Qt's model/view
framework. This is in preparation for making the undo-machinery
compatible with the filtering.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>