- 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

The idea of mapping non-existen characters to space (0x20) was nice alone,
but those maps also used as backward maps for Paste, so space becomes mapped
to last non-existen character on Paste as result.

Fix it by mapping non-existen characters to another non-existen one, i.e. to
0x00, so unused 0x00 can be backward-mapped to some junk without real harm.

Pointed by: Alexander Kabaev <ak03@gte.com>

Add us-ascii_to_cp437 screenmap