The format we use to generate marshal/unmarshal code is from
the spec's tools/extract-formats.py which includes the offset:
we don't use it at all, so rather than having manually-calculated
(and thus probably wrong) values, or 0, emit it altogther.
Reported-by: Christian Decker
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We alternated between using a sha256 and using a privkey, but there are
numerous places where we have a random 32 bytes which are neither.
This fixes many of them (plus, struct privkey is now defined in terms of
struct secret).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>