Previously, every broadcast was attached to a channel, but we can
make it explicit, so when the context is freed, the re-broadcast stops
(if rebroadcast is set).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
In most cases, it's the same as option_anchor_outputs, but for
fees it's different. This transformation is the simplest:
pass it as a pair, and test it explicitly.
In future we could rationalize some paths, but this was nice
and mechanical.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>