[Rivet] updates to FHerwig.cc

[Hendrik Hoeth]

Thus spake Gavin Hesketh (gavin.hesketh at cern.ch):

> I've added the ability to set a couple more FHerwig parameters in
> agile, IAPHIG and RMASS(201). It's a simple extra couple of lines in
> FHerwig.cc (see attached). Can you put this into svn?

Done.

-- 
A man without a dream in his heart already has one foot in the grave.