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

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

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

Approved by: re (implicit)

Delete all GPT partitions at once. (Suggested by Andrey V. Elsukov <bu7cher@yandex.ru>)
Fix amd64 merge script.

Add a file with some remarks for setting up a zfs boot environment

- Add script for preparing disks in GPT/ZFS boot environment
- Add merge script for integrating amd64 slice into i386 disk image

- Build disk image (for USB sticks) and iso image
- Change name to reflect this
- Install all kernel modules
- Choose image size that i386 and amd64 can be combined into one image
- Mount tmpfs over /boot/zfs for zpool imports

- simplify by using one build script
- use label for mounting
- use GENERIC kernel
- create empty Pkg directory

Convert {small prefix}BSD to TERM=xterm as well.

Clean up the ttys files shipped with PicoBSD, NanoBSD and TinyBSD. While
there, it seems one of them still had references to sio(4). Make it in
sync with what we do in the base system.

Remove empty directories from the HEAD.

Discussed with: developers, imp

Remove the uscanner(4) driver, this follows the removal of the kernel scanner
driver in Linux 2.6. uscanner was just a simple wrapper around a fifo and
contained no logic, the default interface is now libusb (supported by sane).

Reviewed by: HPS

Delete files which serve no purpose in this environment.

Inspired by: simon@

Add files to build i386/amd64 bootable rescue ISO images using the
nanobsd framework.