Remove hash_value for unordered containers.

Merged revisions 47463,47465,47522 via svnmerge from 
https://svn.boost.org/svn/boost/trunk

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  r47463 | danieljames | 2008-07-15 22:26:54 +0100 (Tue, 15 Jul 2008) | 1 line
  
  Better hash function for unordered containers. Still a bit rubbish.
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  r47465 | danieljames | 2008-07-15 23:03:15 +0100 (Tue, 15 Jul 2008) | 4 lines
  
  On second thoughts, I'll just completely remove hash_value for ordered
  containers. It's low quality and not very generic (it uses boost::hash for
  mapped values). Should be a painless change.
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  r47522 | danieljames | 2008-07-18 00:08:32 +0100 (Fri, 18 Jul 2008) | 1 line
  
  Remove a mention of the hash functions which I missed before.
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[SVN r47523]

doc/rationale.qbk

@@ -104,8 +104,6 @@ implemented. They are specified
 differently to the standard associative containers, comparing keys
 using the equality predicate rather than `operator==`. This is inconsistent
 with the other containers but it is probably closer to user's expectations.
-I have also added a `hash_value` free function so that the containers can be
-hashed by [classref boost::hash].
 
 [h2 Active Issues and Proposals]