message: Fix to allow copy-assigning ArrayIterators
  This is required to allow passing a pair of Array/ArrayView iterators to
  std::sort().
diff: @@ -57,7 +57,7 @@ protected:
  void advance(IndexType n) { BaseType::m_pos += n; }
  protected:
  - ArrayPointerType const m_arrayPtr;
  + ArrayPointerType m_arrayPtr;
  }; // end of ArrayIteratorBase class
  /// @}
  