cleanup keyboard input handling. run screensaver in a loop until kbhit,

cleanup keyboard input handling. run screensaver in a loop until kbhit,
then break out, THEN worry about user input. Replace scanf nonsense with
simple getch() and keyboard response, since the prompt shown to the user
doesn't say to hit ENTER after typing 1, 2, 3, 4, 6, or 0, or "65536"
for changing the tile variable.