Ensure we log everywhere where we fail due to no_connection_possible

This should make peer disconnection easier to debug.

Author: TheBlueMatt

lightning/src/ln/peer_handler.rs

@@ -755,6 +755,7 @@ impl<Descriptor: SocketDescriptor, CM: Deref> PeerManager<Descriptor, CM> where
 
 											// Unknown messages:
 											wire::Message::Unknown(msg_type) if msg_type.is_even() => {
+												log_debug!(self, "Received unknown even message of type {}", msg_type);
 												// Fail the channel if message is an even, unknown type as per BOLT #1.
 												return Err(PeerHandleError{ no_connection_possible: true });
 											},