Feature: Add NotRoadTypes (NRT)

src/engine_type.h

@@ -14,6 +14,7 @@
 
 #include "economy_type.h"
 #include "rail_type.h"
+#include "road_type.h"
 #include "cargo_type.h"
 #include "date_type.h"
 #include "sound_type.h"
@@ -123,6 +124,7 @@ struct RoadVehicleInfo {
 	uint8 air_drag;          ///< Coefficient of air drag
 	byte visual_effect;      ///< Bitstuffed NewGRF visual effect data
 	byte shorten_factor;     ///< length on main map for this type is 8 - shorten_factor
+	RoadType roadtype;       ///< Road type
 };
 
 /**