This allows for complete channel simulation, including HTLC
transactions, but means we use higher-level primitives to
make the easy.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
These utilities allow us to create valid test txs and information given both
sides' complete set of secrets.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>