Merge all hash changes from trunk.

[SVN r46343]

doc/ref.xml

@@ -1,6 +1,6 @@
 
 <!--
-Copyright Daniel James 2005-2007
+Copyright Daniel James 2005-2008
 Distributed under the Boost Software License, Version 1.0. (See accompanying
 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 -->
@@ -406,6 +406,8 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
         </method>
       </struct-specialization>
 
+      <free-function-group name="Support functions (Boost extension)."> 
+
       <!--
         boost::hash_combine
         -->
@@ -500,6 +502,10 @@ for(; first != last; ++first)
         </para></throws>
       </overloaded-function>
 
+      </free-function-group>
+
+      <free-function-group name="Overloadable hash implementation (Boost extension).">
+
       <!--
         boost::hash_value - integers
         -->
@@ -797,6 +803,7 @@ return seed;</programlisting></entry>
           </informaltable>
         </returns>
       </overloaded-function>
+      </free-function-group>
     </namespace>
   </header>
 </library-reference>