Remove $FreeBSD$: two-line nroff pattern

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

Clean up and improve manual page for fuser(1)

- Mention option's arguments in the list of options (so that now we mention
"-N system" instead of just "-N").
- Stylize signals and other constants like O_APPEND with Dv.
- Sort options.
- Change indentation width for readability.
- Fix a couple of typos.
- Sort symbols list.
- Use Sy instead of Cm for symbols. They are not command modifiers.
- Use Ex -std in the EXIT STATUS section for consistency with other manual
pages.
- Use Ql instead of Dq Li for inline code examples as Li has recently been
deprecated by mdoc.

Reviewed by: bcr
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D25332

use .Mt to mark up email addresses consistently (part3)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

fuser(1) requires a filename.

Reviewed by: lstewart
Approved by: bcr (mentor)
MFC after: 3 days

Remove trailing whitespace per mdoc lint warning

Disussed with: gavin
No objection from: doc
Approved by: joel
MFC after: 3 days

mdoc: reorder sections consistently

- Fix several typos [1]
- fuser(1) writes usernames to stderr, not stdout [1]
- Add history section.

Submitted by: Pieter de Goeje <pieter@degoeje.nl> [1]

- Commit work from libprocstat project. These patches add support for runtime
file and processes information retrieval from the running kernel via sysctl
in the form of new library, libprocstat. The library also supports KVM backend
for analyzing memory crash dumps. Both procstat(1) and fstat(1) utilities have
been modified to take advantage of the library (as the bonus point the fstat(1)
utility no longer need superuser privileges to operate), and the procstat(1)
utility is now able to display information from memory dumps as well.

The newly introduced fuser(1) utility also uses this library and able to operate
via sysctl and kvm backends.

The library is by no means complete (e.g. KVM backend is missing vnode name
resolution routines, and there're no manpages for the library itself) so I
plan to improve it further. I'm commiting it so it will get wider exposure
and review.

We won't be able to MFC this work as it relies on changes in HEAD, which
was introduced some time ago, that break kernel ABI. OTOH we may be able
to merge the library with KVM backend if we really need it there.

Discussed with: rwatson