If you miss a wait event, you can catch up by doing listinvoices and
getting the max of these fields. It's also a good debugging clue.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We don't do it for sendinvoice (yet?).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-EXPERIMENTAL: `fetchinvoice` can take a payer note, and `listinvoice` will show the payer_notes received.