- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

Document the no_warn option.

mdoc(7) police: -xwidth has been fold into -width.

mdoc(7) police: fixed markup, a little bit.

Clean up (and in some cases write) the PAM mudules, using
o The new options-processing API
o The new DEBUG-logging API

Add man(1) pages for ALL modules. MDOC-Police welcome
to check this.

Audit, clean up while I'm here.