cleanup: use std::vector in struct device_table

Since we converted from QString to std::string, let's also use
std::vector instead of QVector. We don't need COW semantics
and all the rigmarole. Let's try to keep Qt data structures
out of the core.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

qt-models/divecomputermodel.h

@@ -27,7 +27,7 @@ slots:
 	void remove(const QModelIndex &index);
 
 private:
-	QVector<device> dcs;
+	std::vector<device> dcs;
 };
 
 class DiveComputerSortedModel : public QSortFilterProxyModel {