explicitly ignore "initialized" message;

--- a/src/Tools/VSCode/src/protocol.scala	Tue Mar 14 14:43:10 2017 +0100
+++ b/src/Tools/VSCode/src/protocol.scala	Tue Mar 14 14:55:00 2017 +0100
@@ -144,6 +144,8 @@
         "documentHighlightProvider" -> true)
   }
 
+  object Initialized extends Notification0("initialized")
+
   object Shutdown extends Request0("shutdown")
   {
     def reply(id: Id, error: String): JSON.T =

--- a/src/Tools/VSCode/src/server.scala	Tue Mar 14 14:43:10 2017 +0100
+++ b/src/Tools/VSCode/src/server.scala	Tue Mar 14 14:55:00 2017 +0100
@@ -356,6 +356,7 @@
       try {
         json match {
           case Protocol.Initialize(id) => init(id)
+          case Protocol.Initialized(()) =>
           case Protocol.Shutdown(id) => shutdown(id)
           case Protocol.Exit(()) => exit()
           case Protocol.DidOpenTextDocument(file, _, _, text) =>