[Rivet] Alpgen interface broken in AGILe 1.1.4

[Piergiulio Lenzi]

Hi!
   it looks to me like the alpgen interface is broken in agile1.1.4.
The Loader looks for a libAGILeAlpgen.so library that is not built 
(actually there is no source file for such a libreary, there is an 
AlpGen.hh header, but no .cc file with the definitions). I'm not even 
sure why we need this, since neither AlpGenFHerwig, nor AlpGenFPythia 
inherit from AlpGen.
Many thanks in advance,
Giulio