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

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

mdoc: consistently spell our email addresses <foo@FreeBSD.org>

Reviewed by: ru

Update my email address.

Assorted mdoc(7) fixes.

o Implement C99 classification macros isfinite(), isinf(), isnan(),
isnormal(). The current isinf() and isnan() are perserved for
binary compatibility with 5.0, but new programs will use the macros.
o Implement C99 comparison macros isgreater(), isgreaterequal(),
isless(), islessequal(), islessgreater(), isunordered().

Submitted by: David Schultz <dschultz@uclink.Berkeley.EDU>