Implement CAN (Cancel, ^X)
Implement CAN (Cancel, ^X)

This helps partially pass t0014-CAN.in, it won't work 100% however
due to the very complex parsing logic of vanilla xterm that
gnome-terminal doesn't even seem to match. xterm's source seems to
have multiple ignore cases for a set of characters such that an
escape sequence like \e!!!!!! prints nothing as the ! continually
gets ignored. Our current logic is we ignore the escape sequence
immediately in this case and print the !.

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