man pages: add missing commas between subordinate and main clauses

jmc@ dislikes a comma before "then" in a conditional, so leave those
untouched.

ok jmc@

Make consistent reference to pathname.

OK schwarze@, jmc@, deraadt@

Document that changes made to the directory hierarchy of the chroot
jail may inadvertanly allow a process to escape. Also mention the
problem of directory fd passing. Based on a diff from deraadt@

Explicitly mention that PATH_MAX includes the NUL in the ENAMETOOLONG
description.

use .In and delete .Tn; from Kaspars at Bankovskis dot net

use .Rv; no change of meaning; from Kaspars at Bankovskis dot net

more library history
facts checked by sobrado@
style tweaks and ok jmc@

Fix typo, setreseuid -> setresuid

ok otto@, jmc@

WARNINGS -> CAVEATS, and a little neccessary cleanup;

encourage use of setreseuid(), and warn there are other privs; ok henning

convert to new .Dd format;

Add example; OK ian@ deraadt@ jaredy@

document EPERM; from Pedro Martelletto;
ok millert@

Remove the advertising clause in the UCB license which Berkeley
rescinded 22 July 1999. Proofed by myself and Theo.

Another round of man page cleanup, this time to remove more hard sentence
breaks and getting rid of short lines, making these files easier to work with.

- For consistency, `super-user' -> `superuser' in all cases.
- Some punctuation fixes.
- Some `id' -> `ID'.

- change references to nil to null; tschroed@acm.org
- remove trailing spaces from end of lines
- add some .Dv
- change -1 to \-1, so `-' is taken as a negative sign
- other misc formatting fixes

remove argument from .Os macros so value in /usr/share/tmac/mdoc/doc-common
is used instead; kwesterback@home.com

make function names the correct case

fix openbsd tag

path/dirname; entropy@tardis.bernstein.com

warn about root and the jail

unescapeable chroot; thanks to nirva and asriel for helping

initial import of NetBSD tree