Transport ship Rally points

I propose a new UI for transport ships.

  1. Set rally point. All units will attempt to rally to this point for the ship when they exit it.
    1b. Set rally point (group) sets the rally points for all transport ships in a group to be a given point.
  2. Clear rally point.
  3. Unload (group) Causes each ship in a group to attempt to unload exactly 1 unit.