Feature: Add NotRoadTypes (NRT)

src/widgets/road_widget.h

@@ -15,6 +15,7 @@
 /** Widgets of the #BuildRoadToolbarWindow class. */
 enum RoadToolbarWidgets {
 	/* Name starts with RO instead of R, because of collision with RailToolbarWidgets */
+	WID_ROT_CAPTION,        ///< Caption of the window
 	WID_ROT_ROAD_X,         ///< Build road in x-direction.
 	WID_ROT_ROAD_Y,         ///< Build road in y-direction.
 	WID_ROT_AUTOROAD,       ///< Autorail.
@@ -26,6 +27,7 @@ enum RoadToolbarWidgets {
 	WID_ROT_BUILD_BRIDGE,   ///< Build bridge.
 	WID_ROT_BUILD_TUNNEL,   ///< Build tunnel.
 	WID_ROT_REMOVE,         ///< Remove road.
+	WID_ROT_CONVERT_ROAD,   ///< Convert road.
 };
 
 /** Widgets of the #BuildRoadDepotWindow class. */