[Patch] First bits of the algo merge

[chris jefferson]

Howard Hinnant wrote:
> ...
> Now you can accommodate proxy iterators AND people who neglect to
> qualify their op== with const. :-)
>
Sorry if I'm stating the obvious, but perhaps the confusion is coming
because the decision we made was to neglect people who don't qualify
their op== with const, but in doing so made proxy iterators work?

Or perhaps I'm talking rubbish..

Chris