This reverts commit ed06bd8a89.

Kill off use of etherboot.h outside drivers/net.

which respond to close with a reopen() (e.g. iSCSI).

xfer_window() function, which can return a scalar rather than a
boolean.

eventually get updated.

provides them.

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

attempt at triggering TCP-related protocols to start).

structures.

DHCP still broken and #if 0'd out.

current working URI.

implement sendto()/recvfrom() equivalents.

allows us to avoid execution loops without having to hack around the
image registration order.

elsewhere as well.