This turned into a more extensive cleanup than intended. The previous
warnings were overlapping and confusing, especially now MPP is the norm.
*warning_capacity* is now the "even under best circumstances, we don't
have enough incoming capacity", which is really what
warning_mpp_capacity was trying to say (no longer printed).
*warning_offline* and *warning_deadends* are only given if adding such
peers would have helped give capacity (i.e. not if *warning_capacity*
is set). The new *warning_private_unused* tells you that we would
have sufficient capacity, but we refused to expose private channels.
The test cases have been enhanced to cover the new warnings.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: JSON-RPC: `invoice` now gives `warning_private_unused` if unused unannounced channels could have provided sufficient capacity.
Changelog-Changed: JSON-RPC: `invoice` warnings are now better defined, and `warning_mpp_capacity` is no longer included (since `warning_capacity` covers that).
We're going to want this for bolt13 formation as well.
As a result of reworking the logic into "candidate selection" then
"route hint selection", we need to change the way round-robin works.
We use a simple incrementing index now.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
