GUI: allow to draw kdSquares

GUI/gtk2.glade

@@ -856,7 +856,8 @@ Public License instead of this License.
 Show convex hull
 Show polygons
 Show polygons intersection
-Show quad tree squares</property>
+Show quad tree squares
+Show kd tree squares</property>
           </widget>
           <packing>
             <property name="expand">False</property>

Graphics/Diagram/Gtk.hs

@@ -23,6 +23,10 @@ diag p obj@(Object _)
       mkDiag (mconcat [quadPathSquare, squares, coordPointsText,
                        coordPoints, polyLines, plotterBG])
              p obj
+  | algo p == 5 =
+      mkDiag (mconcat [kdSquares, coordPointsText,
+                       coordPoints, plotterBG])
+             p obj
   | otherwise = mempty
 diag p objs@(Objects _)
   | algo p == 2 =