Automatically create --no-foo for boolean flag --foo

[cgay]

As discussed here it would be nice to automatically get --no-foo as the negative option for boolean flag --foo.

When negative-names: is provided the automatic --no-foo should not be created. negative-names: #f (or an empty sequence) should disable all negative names.

Honestly not sure whether to support --nofoo, --no-foo, or both. I guess --nofoo is traditional, so potentially less confusing.

See also: #11

[waywardmonkeys]

I'm some things, I'm used to at least 3 different negative options:

• --enable-foo -> --disable-foo
• --with-foo -> --without-foo
• --foo -> --no-foo

But this is also interesting in how it cements an understanding of English into a system...