LHE file production. Production needs CMSSW software, to get consistent
python version. LHE files merging updated for correct NMIX and STOPMIX
blocks in the header (taken from decayed files). Code was re-organized
to fit GRID production, jobs being submitted via ganga. Scripts for
interactive run and for GRID run provided. ganga job splitting scripts
for stop mass from 100 GeV to 500 GeV, assuming undecayed LHE already
copied on the storage element (for GRID production) or a local directory
(for interactive production) are also included. Still some GRID
problems, not clear if not GRID-related (access rights to SE).