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/main.cpp

@@ -120,7 +120,6 @@ int main(int argc, char *argv[])
     installNewTranslator();
 
     qsrand(QDateTime::currentDateTime().toTime_t());
-
     qDebug("main(): starting main program");
 
     MainWindow ui;