(#396) Added fields for min and max depths to the well log plot

Changing those fields will cause all well trace plots to be updated
accordingly.

ApplicationCode/ProjectDataModel/RimWellLogPlot.h

@@ -59,4 +59,7 @@ private:
 
 private:
     QPointer<RiuWellLogPlot> m_viewer;
+    
+    caf::PdmField<double> minimumDepth;
+    caf::PdmField<double> maximumDepth;
 };