Improve and simplify code with modern C++ features

Change-Id: I83bf5513c2a1f90ba5a59e93c473306864b27d94
diff --git a/daemon/table/name-tree-iterator.hpp b/daemon/table/name-tree-iterator.hpp
index 87a93f7..973c961 100644
--- a/daemon/table/name-tree-iterator.hpp
+++ b/daemon/table/name-tree-iterator.hpp
@@ -69,9 +69,15 @@
 
 /** \brief NameTree iterator
  */
-class Iterator : public std::iterator<std::forward_iterator_tag, const Entry>
+class Iterator
 {
 public:
+  using iterator_category = std::forward_iterator_tag;
+  using value_type        = const Entry;
+  using difference_type   = std::ptrdiff_t;
+  using pointer           = value_type*;
+  using reference         = value_type&;
+
   Iterator();
 
   Iterator(shared_ptr<EnumerationImpl> impl, const Entry* ref);