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/ProjectDataModel/RimPlot.cpp

@@ -303,6 +303,14 @@ void RimPlot::handleWheelEvent( QWheelEvent* event )
 {
 }
 
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+bool RimPlot::isCurveHighlightSupported() const
+{
+    return true;
+}
+
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------