Iterator: merge several changes from trunk.

- Update iterator_facade test for #1019
  (header change already merged).
- Category of each iterator is reduced to a known category before we try to
  find a minimum. Fixes #1517.
- `function_input_iterator` from Dean Michael Berris. Fixes #2893
- Fix typo in `boost/iterator.hpp`. Fixes #3434.
- Always include `add_reference` header in iterator adaptor header.

Did not merge changes for #1427.


[SVN r70709]

test/iterator_facade.cpp

@@ -87,6 +87,10 @@ struct input_iter
     }
 };
 
+template <class T, class U>
+void same_type(U const&)
+{ BOOST_MPL_ASSERT((boost::is_same<T,U>)); }
+
 int main()
 {
     int state = 0;
@@ -101,6 +105,8 @@ int main()
     input_iter p;
     (*p).mutator();
     p->mutator();
+
+    same_type<input_iter::pointer>(p.operator->());
     
     return boost::report_errors();
 }