Fix cmd line arguments to allow passing client id and key pair

Before this commit, a user was able to pass a FSD key only via command
line arguments. However, changing the key itself is not enough. The key
always needs to be set together with its corresponding id.

refs #795

src/blackcore/vatsim/networkvatlib.h

@@ -121,8 +121,8 @@ namespace BlackCore
             //! Cmd.line options this library can handle
             static const QList<QCommandLineOption> &getCmdLineOptions();
 
-            //! Key if any from cmd.line arguments
-            QString getCmdLineFsdKey() const;
+            //! Client id and key if any from command line arguments
+            bool getCmdLineClientIdAndKey(int &id, QString &key) const;
 
         private slots:
             void replyToFrequencyQuery(const BlackMisc::Aviation::CCallsign &callsign);