Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

mdoc: drop even more redundant .Pp calls

No change in rendered output, less mandoc lint warnings.

Tool provided by: Nobuyuki Koganemaru n-kogane at syd.odn.ne.jp

Add standard MLINKs.

Provide manual page for the mge(4) device driver.

Xref altq(4).

Move npe.4 to a machine specific manpage subdirectory.