ui: project settings fix

* fixed open folder dialog in project settings.
* changed foreign key relation of component_access from the element to the edge table.

src/app/qt/element/QtDirectoryListBox.cpp

@@ -52,6 +52,9 @@ void QtListItemWidget::handleButtonPress()
 {
 	QFileDialog dialog(this);
 	QListView *l = dialog.findChild<QListView*>("listView");
+
+	dialog.setFileMode(QFileDialog::Directory);
+
 	if (l)
     {
         l->setSelectionMode(QAbstractItemView::SingleSelection);