Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC miscellaneous bug fixes (r228042,228192,230522,232531,233473,233904,
235228,239500,241902,242188,243832,243854,244858,245333). This is mostly
documentation fixes and updates to the default FTP list that got left
behind in -CURRENT.

MFC r228048:
Plug memory leaks and fix open(2) error check.

Reviewed by: nwhitehorn

MFC r226666,226739,226741:
Avoid showing the user some spurious error messages from GEOM [1] and do
provide error messages instead of silent failure if there are no disks
or no network interfaces in the system [2].

PR: bin/161926 [1], bin/161926 [2]
Approved by: re (kib)

MFC r226161:
Avoid magicking into existence sub-partitions due to leftover blocks when
creating new ones by destroying any geom that may have come into
existence immediately after adding a partition. The EBR partition scheme
is particularly enthusiastic about false positives in this case.

Approved by: re (kib)

MFC r226160:
Usability enhancements: do not allow setting a mountpoint on bsdlabel
container partitions, which didn't do anything anyway, and check for
an existing freebsd-boot partition before bothering the user to make one.

PR: bin/160931
Approved by: re (kib)

MFC r226083:
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.

Approved by: re (kib)

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix a typo introduced in r219892 that prevented file system options from
being set correctly.

Approved by: re (kib)

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)

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.

Turn on softupdates by default. We need a UI to set filesystem parameters.

The PC98 gpart module supports labels now.

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!