Source plugins: put a serializer and deserializer in the core plugin for server. NFM demod: fixed deserializer

plugins/samplesource/plutosdrinput/plutosdrinput.h

@@ -18,6 +18,7 @@
 #define PLUGINS_SAMPLESOURCE_PLUTOSDRINPUT_PLUTOSDRINPUT_H_
 
 #include <QString>
+#include <QByteArray>
 
 #include "iio.h"
 #include <dsp/devicesamplesource.h>
@@ -100,10 +101,14 @@ public:
     virtual bool start();
     virtual void stop();
 
+    virtual QByteArray serialize() const;
+    virtual bool deserialize(const QByteArray& data);
+
     virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
     virtual const QString& getDeviceDescription() const;
     virtual int getSampleRate() const;
     virtual quint64 getCenterFrequency() const;
+    virtual void setCenterFrequency(qint64 centerFrequency);
 
     virtual bool handleMessage(const Message& message);