Update to TR1 to better support gcc.

Refactored configuration settings so if the .hpp versions of the headers are included then there's no need to figure out the location of the actual std lib headers.
Updated docs to match.

[SVN r39408]

libs/tr1

@@ -1 +1 @@
-Subproject commit de1870e5f2ce4c647572d84ff840285af857c078
+Subproject commit 973f2b8c3ec3055a6a862ac1c988bf80edc463d5