PHYSICAL TRADE SHIP 0.2.11 (Captain of Industry 0.8.6c)

1. In the normal world-map trade UI, click offers to add them to the cart.
2. Open the Trading Dock inspector.
3. Review the new TRADE SHIP panel and press Order.
4. The complete order is checked and paid atomically. Products are delivered only
   during the unloading phase. All vanilla quick-trade product types are supported.
5. The ship uses the game's path finder, steering, docking and undocking jobs.
   It is hidden from ship lists and consumes no cargo-ship or fleet slot.
6. A new voyage can be ordered after two in-game months. The cart can be prepared
   during the wait.

The voyage, paid manifest, delivery guard, cooldown, and cart are stored in the save.
