tuple: add a few vars useful for the fake
create ntuples for fake estimate

- add --write-tuple option
- initialize+finalize tree
- guess tupleFilenameFromHistoFilename
- fill tree (for now only for CR_HF_high)
fake tuple: also save the lepton source
TupleMaker::fill : fix recursion bug
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)
add SampleUtils.fastSamplesFromFilenames
compute_fake_el_scale_factor: save+fetch histos, plot them, compute sf vs pt1 and eta1, try different selections (work in progress)
add nutple for conversion region

values are ~consistent with what we get from the histograms
(see comparison in my slides from today's WH)
Some things need to be polished, but it's good enough to get
it going and try to make a new fake prediction.
compute_fake_el_scale_factor: also allow conversion sf

added a bunch of options to switch between teh bbcc scale factor
and the conversion one. Also rename some of the histograms/nutple
filenames.
Merge pull request #53 from gerbaudo/fake-tree

Fake tree