connectd is going to end up using this do demux; make it fast and complete.
Fixing this reveals a problem in openingd: it now extracts the channel_id
from funding_signed (which is where we transition off the temporary), and
gets upset. So fix that.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).