[Patch] First bits of the algo merge

[Paolo Carlini]

Paolo Carlini wrote:

>Humpf!
>
>In order to check that everything was fine (also wrt __ops::bind2nd), I
>decided to implement first the full change in v7-branch... and stumbled
>on partial_sort_copy. The problem is that the predicate is both passed
>to helpers working on the result iterators (i.e., make_heap, sort_heap)
>and on a pair (first, result_first). Therefore, *which* value_types?!?
>  
>
Well, maybe the issue is not so serious, because, among the concepts
naturally there is:

      __glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
_OutputValueType>)

and, if I understand correctly, that appear to imply that
<_OutputValueType, _OutputValueType> is fine.

Paolo.