Add LocalMessage

osu.Game/Online/Chat/LocalMessage.cs

@@ -0,0 +1,16 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Online.Chat
+{
+    /// <summary>
+    /// A message which is generated and displayed locally.
+    /// </summary>
+    public class LocalMessage : Message
+    {
+        protected LocalMessage(long? id)
+            : base(id)
+        {
+        }
+    }
+}