Split of tr1 and std random facilities and completion of latter

[Benjamin Kosnik]

> > What is your preferred outcome for C++0x random support in 4.4.0?
> >   
> My preference, at this point, very close to the branching, is
> definitely doing nothing, or at least not committing any large
> change. Simply, we don't have the time to converge on a stable, well
> thought, set of changes. 

OK.

> Actually, I believe the same policy
> (essentially, fixes for regressions and not-extensive - i.e.,
> requiring invasive changes - bugs only) should hold from now on for
> the rest of the library, certainly I will adhere to it for my
> personal work.

Please review the current state of gnu.ver, specifically
GLIBCXX_3.4.11, and let me know if you see anything amiss.

best,
-benjamin