This change is really to allow us to have a --dev-fail-on-subdaemon-fail option
so we can handle failures from subdaemons generically.
It also neatens handling so we can have an explicit callback for "peer
did something wrong" (which matters if we want to close the channel in
that case).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The spec 4af8e1841151f0c6e8151979d6c89d11839b2f65 uses a 32-byte 'channel-id'
field, not to be confused with the 8-byte short ID used by gossip. Rename
appropriately, and update to the new handshake protocol.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>