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]

libs/unordered

@@ -1 +1 @@
-Subproject commit 43506606263ec398caa32d1227429b2fc16ebabe
+Subproject commit 386d9f28d76dfdf1eb787a16be59a153aa6fb47c