Add yet another ugly hack to iscsiboot.c, this time to allow the user to
inhibit the shutdown/removal of the iSCSI INT13 device (and the network
devices, since they are required for the iSCSI device to function).

On the plus side, the fact that shutdown() now takes flags to
differentiate between shutdown-for-exit and shutdown-for-boot means that
another ugly hack (to allow returning via the PXE stack on BIOSes that
have broken INT 18 calls) will be easier.

I feel dirty.

permanent processes, rather than requiring each one to have its own
initialisation function.

do it.

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

dependency on dev.o.

default test to the DHCP test.

Kill off the static single net device and move to proper dynamic
registration (which we need with the new device model).

Break the (flawed) assumption that all network-layer protocols can use
ARP; such network-layer protocols (i.e. IPv4) must now register as an ARP
protocol using ARP_NET_PROTOCOL() and provide a single method for checking
the existence of a local network-layer address.

point trying to use the old boot sequence.  Replaced with a call to the
AoE demo code, so that people can at least build and try something useful.

portions such as the stack) during the installation process.

init_fns() are called from main().  We need to think about initial
control flow some more.

Use %m to print error

initial device, and will also allow for e.g. a device menu to be presented
to the user.

link time to accommodate whatever bus objects are included.

the boot device.

*other* than the main boot device.

out the new probing logic.

call it initialise() and place it in main.c.  :)