- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Merge an applicable subset of r263234 from HEAD to stable/10:

Update most userspace consumers of capability.h to use capsicum.h instead.

auditdistd is not updated as I will make the change upstream and then do a
vendor import sometime in the next week or two.

Note that a significant fraction does not apply, as FreeBSD 10 doesn't
contain a Capsicumised ping, casperd, libcasper, etc. When these features
are merged, the capsicum.h change will need to be merged with them.

Sponsored by: Google, Inc.

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

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

Test process descriptors.

Ensure that process descriptors work as expected. We should be able to:
- pdfork(), like regular fork(), but producing a process descriptor
- pdgetpid() to convert a PD into a PID
- pdkill() to send signals to a process identified by a PD

Approved by: re (kib), mentor (rwatson)
Sponsored by: Google Inc