Variety of fixes

Use z-axis of cards on table to work out which pile under a card is the
most appropriate one
Sunken Treasures has a special end condition (defeating the villain is
not enough)
Ensure all ship options have suitable showIf logic
Ensure cards banished from plunder pile are actually banished, not just
returned to the box
Change the way plunder is added to a ship (2 fns, 1 to roll, 1 to add)