Fixed typo in spec.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403399

dlib/type_safe_union/type_safe_union_kernel_abstract.h

@@ -167,7 +167,7 @@ namespace dlib
         >
     void serialize (
         const type_safe_union<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>& item, 
-        std::istream& in
+        std::ostream& out 
     );   
     /*!
         provides serialization support