Fix deprecation warning

Also put iterator into dhandy namespace. I don't
remember why I left it out, and it's probably a
sign I should have not done so.

include/duckhandy/infix_iterator.hpp

@@ -5,12 +5,12 @@
 #if !defined(INFIX_ITERATOR_H_)
 #define  INFIX_ITERATOR_H_
 #include <ostream>
-#include <iterator>
+
+namespace dhandy {
 template <class T,
           class charT=char,
           class traits=std::char_traits<charT> >
-class infix_ostream_iterator :
-    public std::iterator<std::output_iterator_tag,void,void,void,void>
+class infix_ostream_iterator
 {
     std::basic_ostream<charT,traits> *os;
     charT const* delimiter;
@@ -19,6 +19,13 @@ public:
     typedef charT char_type;
     typedef traits traits_type;
     typedef std::basic_ostream<charT,traits> ostream_type;
+
+	using iterator_category = std::output_iterator_tag;
+	using value_type = void;
+	using difference_type = void;
+	using pointer = void;
+	using reference = void;
+
     infix_ostream_iterator(ostream_type& s)
         : os(&s),delimiter(0), first_elem(true)
     {}
@@ -45,4 +52,5 @@ public:
         return *this;
     }
 };
+} //namespace dhandy
 #endif