This patch extends the embedded image feature to allow multiple
embedded images instead of just one.

gPXE now always boots the first embedded image on startup instead of
doing the hardcoded DHCP boot (aka autoboot).

Based heavily upon a patch by Stefan Hajnoczi <stefanha@gmail.com>.

Some devices take a very long time to initialise.  This can make it
difficult to visually distinguish between the error cases of failing
to start executing C code and failing to initialise a device.

Add a "gPXE initialising devices..." message.  The trailing ellipsis
indicates to the user that this may take some time, and the presence
of the message indicates to the developer that relocation etc. all
succeeded.

__cdecl is a misleading name, since it currently encapsulates both
cdecl and regparm(0) attributes.  Rename to __asmcall.

Some hardware vendors have been known to remove all gPXE-related
branding from ROMs that they build.  While this is not prohibited by
the GPL, it is a little impolite.

Add a facility for adding branding messages via two #defines
(PRODUCT_NAME and PRODUCT_SHORT_NAME) in config/general.h.  This
should accommodate all known OEM-mandated branding requirements.
Vendors with branding requirements that cannot be satisfied by using
PRODUCT_NAME and/or PRODUCT_SHORT_NAME should contact us so that we
can extended this facility as necessary.

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.  :)