- 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 SVN revisions 272278,272379,275874:
r272278: Prevent buffer overflow(s) + style(9) nits
r272379: Optimize program performance + style(9) nits
r275874: Improve feedback to user by using dpv(3)

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

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

Fix segfault if distfetch and distextract binaries are run standalone
without the DISTRIBUTIONS environment variable set.

PR: bin/165492
Submitted by: Fernando Apesteguia
MFC after: 4 days

Plug memory leaks and fix open(2) error check.

Reviewed by: nwhitehorn
MFC after: 3 days

Add some error checking on the return values of chdir() and calloc(). The
first might actually happen, so it displays the error message in a prettier
way.

Found by: Coverity Prevent(tm)
CID: 9121, 9122, 9123, 9124

Import bsdinstall. This is meant to be (eventually in conjunction with
pc-sysinstall) a replacement for sysinstall in the 9.0 release and beyond.
Currently supported platforms are sparc64, pc98, i386, amd64, powerpc, and
powerpc64. Integration into the build system will occur in the coming
weeks.

Merging with pc-sysinstall will use this code as a frontend, while
temporarily retaining the interactive partition editor here. This work
will be done in parallel with improvements on this code and release
integration.

Thanks to all who have provided testing and comments!