Add Debug to derive list in MessageSendEvent

It can be quite useful in debugging, and potentially also so for
users.

Author: TheBlueMatt

lightning/src/util/events.rs

@@ -228,7 +228,7 @@ impl MaybeReadable for Event {
 /// An event generated by ChannelManager which indicates a message should be sent to a peer (or
 /// broadcast to most peers).
 /// These events are handled by PeerManager::process_events if you are using a PeerManager.
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub enum MessageSendEvent {
 	/// Used to indicate that we've accepted a channel open and should send the accept_channel
 	/// message provided to the given peer.