Updated tests to stress new is_convertible and is_base_and_derived improvements.

Updated docs accordingly.


[SVN r17147]

libs/type_traits

@@ -1 +1 @@
-Subproject commit 524468f57940ac81744150e38b00b5ed5d3de95b
+Subproject commit 0572dd371393295a4fdea0d133559548acbb25a5