Fix Track/Bus dialog name-entry default

Changing the track-type to add changes the name which marked the
name-entry as "edited by user", even though it was Ardour itself
which changed the name.

gtk2_ardour/add_route_dialog.cc

@@ -282,6 +282,7 @@ AddRouteDialog::maybe_update_name_template_entry ()
 		name_template_entry.set_text (VCA::default_name_template());
 		break;
 	}
+	name_edited_by_user = false;
 }
 
 void