Discovered forgotten efforts

Went to sync my branch to learn that I had made some changes which, in
my opinion, are actually fairly clever.
;    Users no longer pick a row and then a column. Each tile has a
letter; they just pick the letter.
;    New flip() method in the board class. Keep track of score.

I'll likely integrate a lot of the current code in the gui_terminal.py
straight into flip.py, because very little of it is actually
GUI-specific.

None of these changes are implemented; they are left commented out until
tested.