- ADD a macro OM_HAS_HASH in the config file.

- Based on the macro provide partial specializations for std::hash<>
- for vertex,halfede,edge, and face handles.
- Add a free function hash_value(BaseHandle) for boost::unordered_set/map

src/OpenMesh/Core/Mesh/PolyMeshT.hh

@@ -608,11 +608,6 @@ const LHS mesh_cast(const PolyMeshT<KERNEL> *rhs) {
     return MeshCast<LHS, const PolyMeshT<KERNEL>*>::cast(rhs);
 }
 
-inline size_t hash_value(const VertexHandle&  i)   { return i.idx(); }
-inline size_t hash_value(const HalfedgeHandle&  i) { return i.idx(); }
-inline size_t hash_value(const FaceHandle&  i)     { return i.idx(); }
-
-
 //=============================================================================
 } // namespace OpenMesh
 //=============================================================================