Kill errortab array; it can screw up alignment.

"boot" command to attempt booting from within the command shell, fall back
to shell if boot fails for any reason.

screen sequence doesn't work (like bios_console.c on some platforms).

the option config UI.

Introduce new {show,set,clear}_setting() that take a struct setting *
rather than a const char *.

set_setting() handles calling clear_setting() when appropriate, so that
individual setting types don't have to check for empty strings.

memory" and "no space left for DHCP options"

thinking that a command executed successfully.

call doesn't do it.

command is linked in.

printing in the bottom-right position.