added acknowledgement to Andrei for the conversion class

[SVN r9210]

include/boost/detail/type_traits.hpp

@@ -470,6 +470,9 @@ public:
 template <typename T, std::size_t sz> struct is_POD<T[sz]>
 { static const bool value = is_POD<T>::value; };
 
+//
+// Thanks to Andrei Alexandrescu for the original version of this
+// conversion class!
 //
 // is one type convertable to another?
 template <class From, class To>