Implementation of forward_list (and compressed_pair)

[Paolo Carlini]

Chris Fairles wrote:
> std::tuple already does EBO. its used for example in unique_ptr. no
> need for the extension I think.
>   
This is a known issue, discussed on the reflector (and between me and Ed
in private email). To the best of my knowledge (correct me if I'm wrong)
the current working draft does not require any form of compression, it's
just an optimization of our implementation. Also, compressed pair is a
well known, very simple, extension, already available in some form
elsewhere. All in all, I suggested to Ed to contribute it and use it in
forward_list, also as a step in the direction of the C++0x scoped
allocator model (when instantiated for a pair of allocators).

Paolo.