Added convenience class initialized_value, as announced at http://article.gmane.org/gmane.comp.lib.boost.devel/169833

[SVN r42815]

libs/utility

@@ -1 +1 @@
-Subproject commit 9ed68b832123c2c1d2d459ec89826f8d2fa77800
+Subproject commit 8ce58b1675e81a5249bed6101d4b6186f8be641b