We currently don't handle LOG_IO properly, and we turn it into a string
before handing it to the ->print function, which makes it ugly for
the case where we're using copy_to_parent_log, and also means in
that case we lose *what peer* the IO is coming from.
Now, we handle the io as a separate arg, which is much neater.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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>
