Codes that fix the cross section computation 

1. GenFilterEfficiencyProducer 
 now only efficiency from additional filter is saved in GenFilterInfo.
 JetMatching efficiency is not saved.

2. LHERunInfo.cc
 remove the error from delta2Sig 

3. GenXSecAnalyzer.cc
remove the error from delta2Sig, and also computes cross sections before and after additional filter