[Toybox] [PATCH] scan_key: support more terminals.

[David Seikel]

> > luckily i suspect in 2019 we mainly want function keys just so we
> > can throw them away and get on to the next meaningful keypress! but
> > i can easily put this back to one constant per key if you prefer.  
> 
> Unfortunately a command line utility doesn't get to _see_ the
> function keys, so yeah probably.

Users of mc and mcedit need functioning function keys, though they do
have a backup of Esc $DIGIT, which helps when a lot of X terminals use
F10 for their menus.  I know I long ago tried to get mcedit into toybox.

-- 
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coz there are too many silver coated monkeys in the world.