subIndex for codim 0 enabled.

[[Imported from SVN: r3134]]

grid/alu3dgrid/entity_imp.cc

@@ -426,7 +426,6 @@ namespace Dune {
   struct IndexWrapper<IMPLElemType, hexa, 0>
   {
     static inline int subIndex(const IMPLElemType &elem, int i) {
-      assert(false);
       return i;
     }
   };