(svn r8211) -Codechange: (NewGRF) Implement callback 2D, explicit vehicle colour map

selection.

src/newgrf_callbacks.h

@@ -48,6 +48,10 @@ enum CallbackID {
 	/* Called when building a station to customize the tile layout */
 	CBID_STATION_TILE_LAYOUT        = 0x24,
 
+	/* Called to determine if a specific colour map should be used for a vehicle
+	 * instead of the default livery */
+	CBID_VEHICLE_COLOUR_MAPPING     = 0x2D,
+
 	/* Called when the player (or AI) tries to start or stop a vehicle. Mainly
 	 * used for preventing a vehicle from leaving the depot. */
 	CBID_VEHICLE_START_STOP_CHECK   = 0x31,