[Rivet] NLOHisto1D

[Frank Siegert]

> This is what the "multi-event" branch does, along with handling of
> weight vectors within each (sub)event. Take a look in
> /hepforge/hg/rivet/private/multi-event  I'll let Chris say more about
> the status of this -- as far as I know it's working for 1D histograms
> and just needs a bit of technical work to generalize to wrappers on the
> other YODA data types without masses of unmaintainable code duplication
> -- i.e. some template or macro smartness, preferably without being too
> clever-clever.

Argh, many apologies that I completely forgot about this older thread
in which this was mentioned already!

That also reminds me that I wanted to catch Chris (and anybody else
interested) on Skype to discuss a bit more how we can work towards
re-entrant histogramming. I've got a lecture block just ahead of me,
which probably means it'll be mid-June before I'll actually be able to
spend some more time on this. Chris, I'll ping you eventually, ok?
But anyway it's great that the counter event stuff is already in implementation.

Cheers,
Frank