r1889, lakie: Restores a line in multihead.asm (calculations for movement) which I removed inadvertently. This should fix issues with TE experienced after r1887.
r1888, DaleStan: Fix refitting of trains with only one vehicle.
r1887, lakie: Added the ability to use callback 36 to alter train weight (property 16).
r1886, JGR: Correct attempt to store 32 bit value in 16 bit register, resulting in all ARV movement failing when a trailer or any trailer's parent trailers had a vehicle ID greater than 512, which caused the wrong vehicle to be unstopped upon leaving the depot, with the result that the trailer(s) involved never left the depot, as vehicle status bit 1 (2) has still set (indicating stopped), and possibly resulted in random start/stop status changes of other vehicles.
r1885, DaleStan: Fix crash when updating industry directory after the monthly update removes one.