No more "towire_offer", but "towire_tlv_offer".
This means we double-up on the unfortunately-named `tlv_payload` inside
the onion, but we should rename that in the spec when we remove
old payloads.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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>