RFT plot improvements

* Make curve selection optional to avoid flickering in depth plots
* Replace undefined with zero for some curves
* Add spacing factor for min and max depth

ApplicationLibCode/UserInterface/RiuWellLogPlot.cpp

@@ -181,4 +181,5 @@ void RiuWellLogPlot::performUpdate( RiaDefines::MultiPlotPageUpdateType /* whatT
     int axisShift = alignCanvasTops();
     alignScrollbar( axisShift );
     alignAxes();
+    updatePlotLayouts();
 }