CargoPayment required cargo type to be set as state via SetCargo(). This was error prone as CargoPayment is per consist but cargo type can vary per vehicle part. Additionally if SetCargo was not called then the default "uninitialised" state was cargo slot 0, passengers.
Instead of trying to make sure it is set correctly, remove cargo type from CargoPayment and always pass it explicitly to the PayTransfer/PayFinalDelivery methods.
No longer you can utilize the free (and instant) labour of station
workers, transporting your cargo from one part of the station to
the other. No more!
Based on patch by dP.
