We want to use it in peer_control to generate the transaction, but we
really only need the funding_pubkey.
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>
All the daemons will use a common seed for point derivation, so drag
it out of lightningd/opening.
This also provide a nice struct wrapper to reduce argument count.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
