- 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)

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

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

Stop linking against a direct-mapped virtual address and instead
use the PBVM. This eliminates the implied hardcoding of the
physical address at which the kernel needs to be loaded. Using the
PBVM makes it possible to load the kernel irrespective of the
physical memory organization and allows us to replicate kernel text
on NUMA machines.

While here, reduce the direct-mapped page size to the kernel's
page size so that we can support memory attributes better.