MeasureFakeRate2::getLeptonSource: for data return LS_Unk
FourMom: bugfix setIsTight, add setSource
TupleMaker: define explicit setL[01]FakeAttributes rather than adding pars to fill; also set lep source
MeasureFakeRate2, tuple: assign source and isTight
TupleMaker: split setL0FakeAttributes in two (bugprone, no warning on arg swap); add const getter methods
add importRootCorePackages
skeleton code to compute sf from tuple (so far used to debug tuple yields)