do not trigger computer player when game is restored on app launch

- the purpose is that we want to be able to restore the board position last viewed
  by the user
- this partially reverses the change in 5ecb48b: a computer vs. computer game
  is now only paused when it is restored during app launch; if the game is loaded
  from the archive, the computer player is again triggered as it was before the
  change in 5ecb48b
*very* basic solution for new iPad layout using UISplitViewController

This commit serves as the base for future work. the basic layout is working now,
but there's clearly room for much improvement (e.g. where to place the current
board position view, where to place the discard board position button, layout
bug when a new game is started, if orientation changes while game info view
is displayed the split view is not updated correctly etc.).

The main work has been done in PlayViewController. This is an overview:
- There is now a superview method for each of the subviews of the front-side view
- Obviously the setup and frame calculation methods for those subviews have been
  extensively revised
- Some unnecessary/obvious comments have been removed
- A few method bodies have been relocated within the source file
ItemScrollView can now change its orientation dynamically

This change originally was developed to implement a more dynamic view
layout on the iPad where a device orientation change would also cause an
orientation change in the board position list view. The iPad layout is now
more static and ItemScrollView no longer needs to change its orientation on
the fly. Still, the capability is too useful to throw away, so I am committing
this untested change anyway.
iPad layout now uses table views to list board positions