If the value is "no color&none" report it as "no-color&none" in 'm O'
and for #saveoptions.
Allow "OPTIONS=menu_headings" without any color or attribute value to
mean "no-color&inverse" as it once did before the player could choose
which attribute or color was supported, and matching the default used
when 'menu_headings' hasn't been specified at all.
Accept "OPTIONS=!menu_headings", meaning "no-color&none".
Explicitly reject "OPTIONS=!menu_headings:anything". It was rejecting
that due to blanket rejection of negated option, but reporting "can't
both have a value and be negated" whether there was any value present
or not.
For preselected menu entries when interactively choosing a new value
via the submenu of 'm O', use the current color and attribute rather
than NO_COLOR and ATR_NONE.
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