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

MFC r269289, r269290, r269291, r269292, r269293:

r269289:
sort(1): Remove trailing '.' from See Also section.

r269290:
acpi_wmi(4): Remove trailing comma from standalone Xref.

r269291:
hptiop(4): Remove trailing comma from ending Xref.

r269292:
pf.conf(5): Remove trailing comma from ending Xref.

r269293:
kernel_mount(9): Remove trailing comma from ending Xref.

Sponsored by: The FreeBSD Foundation

MFC r264918:

Fix spelling error.

MFC r264581, r264744:

Various style(9) fixes and typos in printf, grep, sort and patch.

#define should be followed by a tab.

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

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

- Update Oleg Moskalenko's email address

Requested by: Oleg Moskalenko <mom040267@gmail.com>

Remove trailing whitespace.

- Change --nthreads parameter to --parallel for GNU compatibility
- Change default sort method to mergesort, which has a better worst case
performance than qsort

Submitted by: Oleg Moskalenko <oleg.moskalenko@citrix.com>

mdoc: sort sections into conventional order.

- Only use multi-threading for large files
- Do not use mmap() by default; it can be enabled by --mmap
- Add some minor optimizations for -u
- Update manual page according to the changes

Submitted by: Oleg Moskalenko <oleg.moskalenko@citrix.com>

Add a BSD-licensed sort rewrite that was started by me and later completed
with the major functionality and optimizations by Oleg Moskalenko.
It is compatible with the latest version of POSIX and the current GNU sort
version that we have in base. Beside this, it implements all the
functionality introduced in later versions of GNU sort. For now, it will
be installed as "bsdsort", keeping GNU sort as the default sort
implementation.