Initial checkin of new version of Boost.Unordered.

- More template use, less preprocessor use.
 - Removed some of the Visual C++ 6 workarounds.
 - Reduced memory use of the main object.
 - Split into smaller headers.

[SVN r55878]

test/Jamfile.v2

@@ -3,5 +3,7 @@
 # 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)
 
+import testing ;
+
 build-project unordered ;
 build-project exception ;