- 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

MFC revisions 268999, 269027, 269351-269352, 269354, 269460, 270283,
270505, 270954, and 270989:
r268999: Add new bsdconfig example scripts; remove obsolete ones
r269027: Update bsdconfig dot module; fixes and enhancements
r269351: Add setvar() for non-FreeBSD platforms using bash as /bin/sh
r269352: Fix syntax error when run under bash
r269354: Update setvar() function introduced in r269351
r269460: Update f_xdialog_info() in bsdconfig's dialog.subr include
r270283: Add `-A' flag to pkg-install(8) when installing dependencies
r270505: Optimize f_which() to be slightly faster still (common.subr)
r270954: Update f_dialog_init() for safer getopts usage (dialog.subr)
r270989: Fix for previously mentioned r270954

Approved by: re (gjb)

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

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

Import bsdconfig(8) as a replacement for the post-install abilities of
deprecated sysinstall(8). NOTE: WITH_BSDCONFIG is currently required.

Submitted by: Devin Teske (dteske), Ron McDowell <rcm@fuzzwad.org>
Reviewed by: Ron McDowell <rcm@fuzzwad.org>
Approved by: Ed Maste (emaste)