#19 Provide key combination to exit the game

[Marcelo Ruiz]

Quite often, when trying the game under Linux, the graphics freezes. The program still runs but I have no way to kill the program because it runs full screen. The only thing I can do is hit Ctrl+Alt+Backspace to terminate the X server. I think a better way to deal with this will be to have a keyboard combination to exit the game. A dialog could be shown to request the user confirmation (with the default on exit, to be selected with the Enter key in case graphics freeze).