[Rivet] AGILE bugfix for alpgen+herwig

[Gavin Hesketh]

Hello,
A small fix for AlpGenFHerwigJimmy.cc

Line 28 sets the process to -100 (read external events), but this gets 
overwritten to 1500 by FHerwig::initialize(). One line needs to be added:

FC_HWPROC.IPROC = -100;
_iprocset = true;

or replace both these with:

setParam("IPROC", -100);


The same applies to AlpGenFHerwig.cc


cheers,
	Gavin