[Patch, Fortran] PR54339 - Update gfortran.texi's standard refs, status and TS29113 sections

[Tobias Burnus]

* ping *
http://gcc.gnu.org/ml/fortran/2013-01/msg00223.html

Tobias Burnus:
> As promised: A patch for the "regression" PR54339. I am sure there is 
> room for improvement :-)
>
> Everyone: Please feel free to comment on the current documentation, 
> http://gcc.gnu.org/onlinedocs/gfortran/ , and on the attached patch.
>
> OK for the trunk?
>
> Tobias