My node tried to rebuild one of them because it was lagging (I noticed
because mrkd was not installed).
Turns out a few were lagging, and lightning-dev-sendcustommsg.7 was totally
empty!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is needed to fully implement handling of blockheight disagreements
between us and payee.
If payee believes the blockheight is higher than ours, then `pay`
should wait for our node to achieve that blockheight.
Changelog-Add: Implement `waitblockheight` to wait for a specific blockheight.