Add DelFill changes
NEVT filled without weight

After I talked with John, I understand that we shouldn't fill
the nevt with weight
Code for Stacking HT and inclusive samples

HTHis: class for HTbin plots
MCHis: class for inclusive plots (maybe a better name be useful)
HTSample: common interface for HTHis and MCHis,
HTStack : class for actual drawing
Bug fix for boson splitting

missed fabs on the boson ID :-(