And make all the callers choose which one. In general, I prefer warn,
which lets them reconnect and try again, however some places are either
stated that they must be errors in the spec itself, or in openingd
where we abandon the channel when we close the connection anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Changed: Protocol: we now send warning messages and close the connection, except on unrecoverable errors.