Add missing feature rememberance to client (#2275)

Fix #2249
Add the ability for the client to remember the missing features that it
received from the server it last connected to and not display the
"missing/optional feature" message at every login.

cockatrice/src/remoteclient.h

@@ -45,6 +45,8 @@ private:
     QByteArray inputBuffer;
     bool messageInProgress;
     bool handshakeStarted;
+    bool newMissingFeatureFound(QString _serversMissingFeatures);
+    void clearNewClientFeatures();
     int messageLength;
     
     QTimer *timer;