We have a seed, which is for (future!) unit testing consistency. This
makes it change every time, so our pay_direct_test is more useful.
I tried restarting the noed around the loop, but it tended to fail
rebinding to the same port for some reason?
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Also, we split the more sophisticated json_add helpers to avoid pulling in
everything into lightning-cli, and unify the routines to print struct
short_channel_id (it's ':', not '/' too).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>