[Rivet] Z projection on Rivet

[Frank Siegert]

>> >> 1) calculate the mass after adding the photons, if the photons are
>> >> going to be added (probably a tiny effect)
>>
>> What about the pT and eta cuts, also after photons are added or before?
>
> After. If the photons are going to be added, they should be added to the
> nearest electron before any cuts are applied; it's equivalent to cutting
> on calorimeter-based objects.

After a rewrite of the ZFinder I believe that all features are 
implemented now. I have re-validated all affected analyses and they look 
basically identical to before (no big surprise).

Gavin, please let me know if you find anything that still looks 
incorrect to you. Also, independent from the ZFinder changes... could 
you take a look at the following two analyses and check whether you 
think the particle level cuts are implemented correctly?

D0_2008_S6879055
  - dR(l,j) cut necessary?
  - can we use ZFinder here as well?

CDF_2009_S8383952
  - shape looks a bit funny in my plots

Cheers,
Frank