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

Fix typo: s/partion/partition/

Submitted by: Marc Balmer <marc@msys.ch>
MFC after: 3 days

Added the IPLware 3.33 support.
- Added magic numbers to pretend the NEC original program version
2.70.
- Added string display routine with Shift-JIS code support.
- Added three nop instructions at start1 in start.s since the
installaer of the IPLware put 'call $0x09ab' instruction.
- Put the near return instruction at 0x9ab in selector.s.

Since the Shit-JIS display routine must be located at 0x1243, the
linker script file (ldscript) is applied.

- Fixed missing initialization of current device number.
- Fixed comment.

Pointed out by: nyan

Added PC-98 HDD boot manager. The boot0 is the `IPL' which occupies
sector 0 of a disk and boot0.5 is the `boot selector' which starts
from address 0x400. The IPL loads boot0.5 and boot0.5 loads bootblock
of a slice.

The boot manager stuff was developed by me (kato) with Borland C++,
and then, translated into bcc in the ports collection by Nokubi-san.
After that, boot0 has been translated into gas with the .code16
directive by Takahashi-san (nyan) and boot0.5 has been rewritten in
gas by me.