Removed broken trick

Doesn't work anymore without implicit conversions between P and WP

Periodic_3_triangulation_3/include/CGAL/Periodic_3_Delaunay_triangulation_3.h

@@ -505,10 +505,7 @@ public:
       if (pbegin == points.end()) return number_of_vertices() - n;
     }
 
-    // Use Geom_traits::K for efficiency: spatial_sort creates a lot
-    // of copies of the traits but does not need the domain that is
-    // stored in it.
-    spatial_sort (pbegin, points.end(), typename Geom_traits::K());
+    spatial_sort (pbegin, points.end(), this->geom_traits());
 
     Conflict_tester tester(*pbegin,this);
     Point_hider hider;