We have various functions to convert to a string, rename them all so we can
count on fmt_X being the formatter for struct X, and make them all return
`char *`.
Sometimes they existed but were private, sometimes they had a
different name. Most take a pointer, but simple types pass by copy:
short_channel_id, amount_msat and amount_sat.
The following public functions changed:
1. psbt_to_b64 -> fmt_wally_psbt.
2. pubkey_to_hexstr -> fmt_pubkey.
3. short_channel_id_to_str -> fmt_short_channel_id (scid by copy now!)
4. fmt_signature -> fmt_secp256k1_ecdsa_signature
5. fmt_amount_sat/fmt_amount_msat pass copy not pointer, return non-const char *.
6. node_id_to_hexstr -> fmt_node_id
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>
> If the peer's revocation basepoint is unknown (e.g. `open_channel2`),
> a temporary `channel_id` should be found by using a zeroed out basepoint
> for the unknown peer.
v2 of channel open uses the channel revocation basepoints to calculate
the channel_id, instead of the funding_txid + outnum
Moving away from the funding_txid opens the way for splicing + rbf
