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

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

Updates for netgraph node manual pages.

Discussed with: glebius
Submitted by: Mamontov Roman <mr.xanto@gmail.com>

Remove trailing whitespace per mdoc lint warning

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

Manual page for Predictor-1 PPP compression netgraph node.

Submitted by: Alexander Motin <mav alkar.net>