Add Pong CM

src/main/kotlin/com/shr4pnel/ferretirc/net/messages/ClientMessage.kt

@@ -110,4 +110,9 @@ sealed class ClientMessage(val strName: String) {
         override val trailing: String
             get() = message
     }
+
+    class Pong(val token: String) : ClientMessage("PONG") {
+        override val trailing: String
+            get() = token
+    }
 }