[Patch] First bits of the algo merge

[Paolo Carlini]

Howard Hinnant wrote:

> The demo is set up with an example which breaks under A, but not 
> under B and C.

ARRGGHH!!! You cannot say that so quickly!

You mean, committing the current simple version of the algo
simplification, would break some code that currently is fine in
mainline! This is TOTALLY bad.

Either we commit the new version or do nothing, but we badly need a
decision.

Paolo.