Fix Realtime widgets compiler warnings

.. they hide real issues.

qxt/src/qxtspanslider.cpp

@@ -200,6 +200,8 @@ void QxtSpanSliderPrivate::triggerAction(QAbstractSlider::SliderAction action, b
     case QAbstractSlider::SliderMove:
         if ((main && mainControl == QxtSpanSlider::UpperHandle) || (!main && altControl == QxtSpanSlider::UpperHandle))
             up = true;
+        no = true;
+        break;
     case QAbstractSlider::SliderNoAction:
         no = true;
         break;

src/Train/MeterWidget.cpp

@@ -115,7 +115,7 @@ QSize MeterWidget::minimumSize() const
     return QSize(m_Width, m_Height);
 }
 
-void MeterWidget::startPlayback(Context* context)
+void MeterWidget::startPlayback(Context* )
 {
 
 }

src/Train/NullController.cpp

@@ -55,7 +55,7 @@ bool NullController::find() {
     return true;
 }
 
-void NullController::setMode(int i) {
+void NullController::setMode(int ) {
     restart();
 }
 

src/Train/RealtimeController.cpp

@@ -176,7 +176,7 @@ void RealtimeController::processRealtimeData(RealtimeData &rtData)
 
 // Wrap static array in function to ensure it is init on use, which is after PolyFitGenerator
 // who is static init at load time.
-const VirtualPowerTrainer * const PredefinedVirtualPowerTrainerArray(size_t &size) {
+const VirtualPowerTrainer * PredefinedVirtualPowerTrainerArray(size_t &size) {
 
     static const VirtualPowerTrainer s_PredefinedVirtualPowerTrainerArray[] =
     {