with GNU groff – add some special handling to the BSD mdoc macros for it so
that the manual pages look good in both utf8 and ps (PDF) mode; also fix in
mksh wrong display of ` (groff: ‘), ' (groff: ’), \' (groff: ´), \- (groff:
U+2212 −), the en dash (nroff doesn’t have it, use the em dash there ONLY),
and ~ and ^ (groff: placed atop and size-reduced, for use as diacritics, in
manual pages bad since these are control characters there)
→ PDF manpage now has ‘’ “” and good-looking hyphens and mini and ~ and ^
→ utf8 manpage now has ‘’ “”, good-looking hyphens, cut’n’pasteable mini
→ nroff manpage still has '' "" instead of ugly `' ``'' or even `´
→ Debian lintian won’t complain any longer