Tidy up of the display so things don't get thrown off when the scrollbar kicks in.
1.1.0
This release makes a simple improvement to the display of keys that can't be printed. Before it just left that cell in the display empty, now it either tells you if the `char` of the event is `None`, or if it as `not is_printable` and if the latter it shows the numeric value of `char` too.