Tiles are now labeled & selected via letters

flip.py
;    Implemented lettered tiles
;    Removed Tile.flip() returning the score
;    Added Board.flip() (which modifies the score)
;    Still contains a lot of the gui_terminal elements
gui_terminal.py
;    Modified tile selection to account for letters
;    Fixed a bug causing 'flip' to translate to 'note'
;    Added a silly debug instance