RFT file improvements

* Guard null pointer access
* Delay open of RFT files until data is requested
When opening ensemble summary cases, the opening of RFT files can take some time. Avoid this by delaying the file open operation.

* Fix infinite update loop for RFT plots
* Avoid moving the tracker line when clicking in the plot

ApplicationLibCode/Application/RiaGuiApplication.cpp

@@ -1210,7 +1210,7 @@ void RiaGuiApplication::onProjectBeingOpened()
     // When importing a project, do not maximize the first MDI window to be created
     m_maximizeWindowGuard = std::make_unique<RiuMdiMaximizeWindowGuard>();
 
-    m_mainWindow->setBlockSubWindowActivatedSignal( true );
+    if ( m_mainWindow ) m_mainWindow->setBlockSubWindowActivatedSignal( true );
     if ( mainPlotWindow() ) mainPlotWindow()->setBlockSubWindowActivatedSignal( true );
 }
 
@@ -1272,7 +1272,7 @@ void RiaGuiApplication::onProjectOpened()
 
     processEvents();
 
-    m_mainWindow->setBlockSubWindowActivatedSignal( false );
+    if ( m_mainWindow ) m_mainWindow->setBlockSubWindowActivatedSignal( false );
     if ( mainPlotWindow() ) mainPlotWindow()->setBlockSubWindowActivatedSignal( false );
 
     // Make sure to process events before this function to avoid strange Qt crash