Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Minor mdoc improvements.

mdoc: sort prologue macros.

Don't use col(1) since grotty(1) never outputs reverse line feeds,
and because col(1) mangles ANSI color escapes if enabled. Spaces
to tabs compression is now done by passing -h to grotty(1).

Discussed with: uqs

Typo.

Implementaiton of man, manpath, whatis, and apropos written entirely in sh.

Features of this new version in favor of the old one:
BSD licensed -- old one is GPL.
Imports configuration from /etc/man.conf and LOCALBASE/etc/man.d/*.conf
allowing ports to extend the base functionality. The pluggable
configuration can supplement the manual search path (retiring use.perl),
add locales, and override language specific toolsets (attempt to merge
the japanese/man port into the base system as much as possible).

Much effort has been made to make this version mirror the functionality
of the existing implementation. For 99% of users, it should be a drop in
replacement.

PR: gnu/143271, gnu/4419
Reviewed by: dougb (previous versions)
Approved by: wes (mentor)