(svn r26872) -Change: give the disaster vehicles the same treatment as aircraft in r26866; make the ascend and descend if needed to cross high mountains (based on patch by ic111)

src/disaster_vehicle.h

@@ -39,6 +39,7 @@ enum DisasterSubType {
 struct DisasterVehicle FINAL : public SpecializedVehicle<DisasterVehicle, VEH_DISASTER> {
 	SpriteID image_override;            ///< Override for the default disaster vehicle sprite.
 	VehicleID big_ufo_destroyer_target; ///< The big UFO that this destroyer is supposed to bomb.
+	byte flags;                         ///< Flags about the state of the vehicle, @see AirVehicleFlags
 
 	/** For use by saveload. */
 	DisasterVehicle() : SpecializedVehicleBase() {}