Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

- Remove separate handling of /bin and /usr/bin in manpath. They are no
longer a special case.
- Prefer PREFIX/share/man over PREFIX/man.
- Add /usr/local/share/man to man_default_path.
- Update manpath man page.

Reviewed by: bapt

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

SEE ALSO should sorted by manpage section first.

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)