drop code oriented on the stream lock in parallel updates

This fact caused by the qt signal-slot implementation. Even if slots
code is going into parallel they will be called in the main app thread.
And also it is used inside KF5 dataengine implementation, so I'm affraid
that it could not be optimized w\o backend rewriting

sources/awesome-widget/plugin/awdataengineaggregator.h

@@ -23,8 +23,6 @@
 #include <QObject>
 
 
-class QTimer;
-
 class AWDataEngineAggregator : public QObject
 {
     Q_OBJECT
@@ -37,13 +35,9 @@ public:
     void setInterval(const int _interval);
 
 signals:
-    void startTimer();
     void updateData(const QString sourceName, const QVariant value, const QString units);
 
 public slots:
-    // additional methods to control this and visualization
-    void connectVisualization();
-    void disconnectVisualization();
     void dropSource(const QString source);
     void reconnectSources();
     // data engines operations
@@ -55,7 +49,6 @@ private:
     void initDataEngines();
     QHash<QString, Plasma::DataEngine *> m_dataEngines;
     int m_interval;
-    QTimer *m_timer = nullptr;
 };