Import: add trip_table argument to DiveImportedModel::repopulate()

In the future we want to download trips into a distinct trip-table
instead of the global trip-table to allow for undo of import.

Therefore add a trip_table argument to DiveImportedModel::repopulate()
and a trip_table member to DiveImportedModel. To correctly set these,
add a DownloadThread::trips() function, which currently simply returns
the global trip table.

Finally, make "struct trip_table *" a Q_METATYPE, so that the corresponding
arguments can be passed from QML.

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

mobile-widgets/qml/DownloadFromDiveComputer.qml

@@ -28,7 +28,7 @@ Kirigami.Page {
 		id: downloadThread
 
 		onFinished : {
-			importModel.repopulate(table)
+			importModel.repopulate(table, trips)
 			progressBar.visible = false
 			if (dcImportModel.rowCount() > 0) {
 				console.log(dcImportModel.rowCount() + " dive downloaded")