work around limitations in real-mode virtualisation support on Intel
VT-capable chips.

Added redundant call to get_memmap() in int13_boot() immediately
before jumping to boot sector, to assist in debugging.

main tree yet, but reserving the error numbers now avoids problems later).

to construct DHCP packets suitable for Infiniband.

the assert message's file and line number gives some clue as to the
real location of the problem.

Added similar assertions to list.h.

implement the -e option.

(Thanks to Jim McQuillan for this suggestion.)

(Problem observed by Clay McClure in VMware Fusion.)

order in which they occur.

Conflicts:

	src/include/compiler.h
	src/include/readline/readline.h

created by strings branch merge. resolved.

require that we use drive 0x80, so it should probably be the default.