[c++0x] unique_ptr.hpp implementation

[Paolo Carlini]

... and, certainly we don't want this in the tuple in std::tr1:

#ifdef __GXX_EXPERIMENTAL_CXX0X__
        _Head_base(_Head && __h) : _M_head_impl(forward<_Head>(__h)) {  }
#endif

as you can see, we have now infrastructure for separate TR1 and C++0x 
implementations of such facilities. For compatibility reasons too, I 
would probably suggest, in such case, to leave the TR1 version alone and 
modify the C++0x version only (that in /include/std, to be clear)

Paolo.