Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Improve error handling and remove an unnecessary check on geom provider
type. GEOM provider names can't duplicate (or shouldn't -- devfs will either
break or only use the first one if they do) so using the first provider
by that name is a sufficient check. This also lets the scripted partitioner
install onto gmirror and geli and such things.

Add a simple scripted partitioner. Documentation and more scripting support
will come soon. This lets the install process have a line like:

bsdinstall scriptedpart 'ada0 GPT {1.5G freebsd-ufs /, 10G freebsd-swap,
auto freebsd-ufs /usr}'

to set up a system with a 1.5GB /, some swap space, and a /usr using the
rest of ada0.

MFC after: 1 month

If invoked as sade, don't complain about having a filesystem on / already
-- it's something you expect (and indeed hope for).

MFC after: 1 week

Warn if trying to install over an existing partition, which usually fails
anyway due to libarchive not being able to overwrite schg flags.

PR: bin/164278
MFC after: 4 days

Provide an error message instead of silent failure if no disks are present
in the system.

PR: bin/161950
MFC after: 3 days

Implement support for GRAID volumes in the installer partition editor,
rename a few options, clarify some help text, and add help text for the
buttons on the main partition editor screen.

Approved by: re (kib)

Add an extra tab between fs_file and fs_vfstype

Reviewed by: nwhitehorn

Only validate the partition setup when the user presses "Save". If the user
wants to exit without saving, it's not a problem if the disk is set up
in an invalid way.

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!