It's just a sha256_double, but importantly when we convert it to a
string (in type_to_string, which is used in logging) we use
bitcoin_txid_to_hex() so it's reversed as people expect.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Except for the trivial case of u8 arrays, have the generator create
the loop code for the array iteration.
This removes some trivial helpers, and avoids us having to write more.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rusty Russell