[Rivet] Rivet 2.1.1 & YODA 1.0.6 soon?

[David Grellscheid]

> I don't have a convenient way to test these, although it was already 
> done by the expts... can anyone else help, or shall I ask the ATLAS
> & CMS Rivet contacts to take a look at the tidied-up code?

Yes, we should definitely feed it back to them first for testing.
Otherwise it would have to go in as "unvalidated".

I'll check Frank's modification, but these

> header tidying, improvement of momentum comparison/sorting machinery,
> and have added some first helper methods to Particle for studying
> decay chains without having to drop into HepMC-land,

need to be checked before we can release.

  David