Commit 2013.11.23 -- cxxomfort conformance.

Added forwarding headers for foreach, optional, local_function
 and typeof that redirect to the features already available
in cxxomfort.

Added basic `iterator` support: iterator base, indirect and transform.

Fixed some implementation details for `<random>` stuff.

Moved the _tr1_ transparent headers to their own subdirectory so that
they can work added in a project/compiler include path.