fts(3): Don't use top-level .Sh sections for functions

The list of possible .Sh sections in a man page is kinda limited
(think DTD, or schema). As a minimal fix use .Ss sub-sections for
now. It might be better to use tagged list with .Fn items that repeat
the arglist so that when you read the descriptions of the arguments
you actually see them, but that requires more intrusive editing.

fts(3): don't use (incorrect) custom -width with .Bl -tag

Default widths are good enough.

fts(3): indent and untabify FTSENT definition

fts(3): use Pq for longer phrases

In PostScript output the extra breathing space that .Pq adds imrpoves
readability of parenthetical clauses.

fts(3): NUL (character) is not a Dv

fts(3): structures are Vt not Fa

Explicitly note that on error, fts_open() returns NULL and sets errno.

This uses the same language as used by OpenBSD's fts_open(3).

branches: 1.31.40;
Strings are NUL-terminated, not NULL-terminated.

branches: 1.30.4; 1.30.10;
Improve -width.

It was nice to expect fts(3) to appear in the '88 revision. But perhaps
people had too high hopes.

Use .In for header files instead of .Ar Pa and variations.

Simplify a clunky multi-line Fn, correct Nm usage, use Dq for quotes, add
some commas.

Bump date for last.

Add bits about FTS_WHITEOUT & FTS_W.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22280, verified by myself.

Use
.In header.h
instead of
.Fd #include \*[Lt]header.h\*[Gt]
Much easier to read and write, and supported by groff for ages.
Okayed by ross.

\-1 and .Dv NULL.

Generate <>& symbolically.

Standardize section headers, sort sections, sort SEE ALSO, punctuation
and misc. fixes.

Boring whitespace fixes.

branches: 1.18.8;
xref symlink(7)

branches: 1.17.4;
Change occurrences of "UNIX" to .Ux or .At as appropriate.

Principally, change foo(N) to .Xr foo N
Also, do some other mdoc tagging.

add LIBRARY section to man page

add missing .Nm entries. from spz@serpens.swb.de.

branches: 1.13.2;
fix type of fts_open() argument; from Enami Tsugutomo in PR lib/3368.

fix 3364 from enami tsugutomo -- FTS ftsp -> FTS *ftsp

merge with Lite, keeping local changes. Also use new Id format.

Mostly sync with CSRG.

minor fixes

Use "Er" for argument to -width in the lists in the ERROR sections so that
formatting is consistant.
Other misc. tweaks.

I've been informed that the fts family of functions is being considered
for a _future_ edition of 1003.1.
I recovered the STANDARDS section, and reworded it slightly so it is
clear that we are talking about a future edition instead of 1003.1-88.

nuke comments re: posix, per jtc. this isn't spec'd by posix.

update to latest version; no *significant* changes.

Fts may be great, by we can't claim it's a superset of POSIX.1 since
fts isn't part of POSIX.1 (or POSIX.2 either).

Add RCS identifiers.

Latest versions from uunet.

branches: 1.1.1;
Initial revision