- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

If no partition configuration is specified in {}, use the automatic setup
the interactive installer uses.

Example: bsdinstall scriptedpart ada0
Result: Use entire disk for a FreeBSD system with default partition layout

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

Work around some behavior of gpart that I absolutely do not understand in
order to make every operation of the partition editor fully revertable.
Under *no circumstances* will it any longer touch the disks until the user
presses Finish and confirms it.

MFC after: 3 days

Allow setting of parameters for file systems (e.g. softupdates), turn on
SUJ by default, and allow creation and mounting of FAT filesystems from
the installer.

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!