Remove *and* delete items once no longer in results

There was a memory leak: i was not deleting the elements from the QList
once they are no longer in the results of the SQL query.

src/timelinelistmodel.cpp

@@ -154,6 +154,7 @@ void TimelineListModel::fetch()
         }
         if (itemsRow < m_items.count()) {
             beginRemoveRows({}, itemsRow, m_items.count() - 1);
+            qDeleteAll(m_items.begin() + itemsRow, m_items.end());
             m_items.remove(itemsRow, m_items.count() - itemsRow);
             endRemoveRows();
         }