std::string overloads for xfstream

[Paolo Carlini]

Smith-Rowland, Edward M wrote:
> Here is the corrected patch.
>
> The references to the standard are correct as of the mailing yesterday ;-)
>   
Good, but I would say let's remove the references anyway, the new
standard is not final yet. I would not ask you to do that if I had not
noticed that the trailing blank lines are still there... Also, while you
are at it, being compile-only testcases, you can also remove the mains.

Thanks,
Paolo.