separating includes: tr1 from c++0x

[Benjamin Kosnik]

> > Paolo and I discussed this briefly in Zurich.
> Actually, we were in Rapperswil ;)

Right!

> >  Paolo, your thoughts? I
> > think we were in general agreement on this. The scope of the work is
> > not huge, and will enable us to make the C++0x includes a bit
> > cleaner. 
> I'm absolutely in favor. Right now the work is rather trivial, very
> little remains in common: both Jon and I gradually split again the
> code when the divergences became too big.

Cool. I see the following left in include/tr1_impl:

boost_sp_counted_base.h  
cinttypes  
cstdint  
cwchar   
type_traits
cctype                   
cmath      
cstdio   
cwctype  
utility
array  
cfenv                    
complex    
cstdlib  
regex

I am proposing that these be split into separate tr1 and include/bits
versions, as applicable. 

-benjamin