Fix #7119: When rotating a ship, apply an additional offset to avoid movement glitch.

src/ship.h

@@ -29,6 +29,8 @@ struct Ship FINAL : public SpecializedVehicle<Ship, VEH_SHIP> {
 	TrackBitsByte state;    ///< The "track" the ship is following.
 	ShipPathCache path;     ///< Cached path.
 	DirectionByte rotation; ///< Visible direction.
+	int16 rotation_x_pos;   ///< NOSAVE: X Position before rotation.
+	int16 rotation_y_pos;   ///< NOSAVE: Y Position before rotation.
 
 	/** We don't want GCC to zero our struct! It already is zeroed and has an index! */
 	Ship() : SpecializedVehicleBase() {}