- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r279385, r279902, r281412:

Merge latest dts files (commit c8c1b3a77934768c7f7a4a9c10140c8bec529059)
from the git tree.

File names with commas in them cause issues for freebsd-update. We
don't actually use these files at the moment, so eliminate them until
we actually do. In the mean time, freebsd-update will be updated
to eliminate the issues.

The GNU Amlogic DTS files have some errors (e.g. bad register
address, bad IRQ, etc) which are fixed by this patch.

MFC r271143, r271151: Reimport dts from vendor branch after proper trim.

Reimport dts files from vendor repo now that it has been properly
trimmed.

Import from rebasing repo at b78b6b80 (new files)