- 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 r276419:

Move the explanation for examples before the example itself. Add
numerous QEMU examples and explanations supplied by sbruno, with thanks
to Ingo Schwarze for help with the mdoc markup. Code, text, testing,
proofreading, cinematography, stunts, and the haunting theme song
supplied by sbruno.

MFC r264269, r264282, r264280, r264291, r264276, r264314

Merge sson's binmiscctl and image activator features to stable/10

Submitted by: sson@freebsd.org

Add Stacey Son's binary activation patches that allow remapping of
execution to a emumation program via parsing of ELF header information.

With this kernel module and userland tool, poudriere is able to build
ports packages via the QEMU userland tools (or another emulator program)
in a different architecture chroot, e.g. TARGET=mips TARGET_ARCH=mips

I'm not connecting this to GENERIC for obvious reasons, but this should
allow the kernel module to be built by default and enable the building
of the userland tool (which automatically loads the kernel module).

Submitted by: sson@
Reviewed by: jhb@