- 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

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

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

More-accurately replicate the help system from sysinstall(8). However, also
improve upon the system by giving the user a "Help" button instead of requiring
the user to press F1.

NOTE: In FreeBSD-9 and higher, dialog(1) does not support the F1 hook, so the
mechanism for providing help to the user had to be changed to a button.

This now means we can resurrect *.hlp files from usr.sbin/sysinstall/help/ as-
is and reusing them as-needed in bsdconfig (holding to the goal of losing as
little functionality from sysinstall as possible).

Reviewed by: adrian (co-mentor)
Approved by: adrian (co-mentor)