MatrixPrediction::Process: closer to Plotter::Process
MatrixPrediction : format dbg info in separate functions (dilepDetails, eventDetails)
move histogram initialization to a separate function initHistos
MatrixPrediction drop un-needed macros, fix indentation
MatrixPrediction::Process: fill the same histos as for SusyPlotter
when doing fakes, push back the list of fake syst

Details:
there are two enums of systematic variations: one is the std one, the
other list contains the variations that are used to determine the
uncertainty on the fakes.  The second one is needed when running
fakepred.
fillFakeHistos: drop confusing sys default value
compute weight for each fake-sys variation