wireproto: add known([id]) function
known([Node]) -> [1/0]
Returns 1/0 for each node, indicating whether it's known by the server.
Needed for new discovery protocols introduced in later patches.
wireproto: fix decodelist to properly return empty list
Needed by tests for next patch introducing known().
debug: add debugwireargs to test argument passing over the wire
Tests argument passing locally, via HTTP, and via SSH. This is mainly preparation
for the next patch.
merge: avoid unlinking destination of merge when case changes (
issue2715)