refs #239, added a helper class for timer based pulls

* changed user componet to use new component
* all new components (aircraft, ATC stations) will use this timer
* it is implemented as "has a" timer based component, as inheriting from 2 QObjects would be problematic

src/blackgui/timerbasedcomponent.cpp

@@ -0,0 +1,29 @@
+#include "timerbasedcomponent.h"
+
+namespace BlackGui
+{
+
+    CTimerBasedComponent::CTimerBasedComponent(const char *slot, QObject *parent) :
+        QObject(parent), m_timer(nullptr)
+    {
+        this->m_timer = new QTimer(this);
+        this->connect(this->m_timer, SIGNAL(timeout()), parent, slot);
+    }
+
+    CTimerBasedComponent::~CTimerBasedComponent()
+    {
+        this->m_timer->stop();
+        this->disconnect(this->parent());
+    }
+
+    void CTimerBasedComponent::setUpdateInterval(int milliSeconds)
+    {
+        if (milliSeconds < 100)
+            this->m_timer->stop();
+        else
+        {
+            this->m_timer->setInterval(milliSeconds);
+            if (!this->m_timer->isActive()) this->m_timer->start();
+        }
+    }
+} // guard