Add support for draft/event-playback

lib/irc.js

@@ -533,3 +533,14 @@ export function parseMembershipModes(str) {
 	}
 	return memberships;
 }
+
+export function findBatchByType(msg, type) {
+	var batch = msg.batch;
+	while (batch) {
+		if (batch.type === type) {
+			return batch;
+		}
+		batch = batch.parent;
+	}
+	return null;
+}