This is required for transactions which use OP_CSV to lock outputs for
a given amount of time: we need to know the mediantime of the block
they were included into.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Because we use the bitcoin wallet to create the anchor transaction, we
need to make sure it doesn't broadcast it; safest to check their config
for the option.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>