New hash API: Update

[Johannes Pfau]

Am Sun, 24 Jun 2012 18:21:06 +0200
schrieb David <d at dav1d.de>:

> Am 24.06.2012 18:13, schrieb Masahiro Nakagawa:
> > I disagree this point. The name 'util' does not make any sense.
> > 'util' seems to be very subjective.
> >
> 
> Right `util` can be everything.
> 

Yep that's the idea. You put everything in there which is not important
enough to be in the std. namespace, but which also doesn't fit into
another submodule either.

For example I don't think uuid should be in the top-level std namespace.
But where to put it then?