(#499) Added a custom track delete feature

Added infrastructure needed to delete track from plot and plot
collection

ApplicationCode/UserInterface/RiuWellLogPlot.h

@@ -46,6 +46,7 @@ public:
     RimWellLogPlot* ownerPlotDefinition();
 
     void insertTrackPlot(RiuWellLogTrackPlot* trackPlot);
+    void removeTrackPlot(RiuWellLogTrackPlot* trackPlot);
 
     void setDepthRangeAndReplot(double minDepth, double maxDepth);