Add multilepton DecFiles: light hadrons -> 4 leptons; B -> multilepton + K
Adds the following decays:
- phi->4mu
- phi->2mu2e
- eta->4mu
- eta->2mu2e
- B->K4mu
- B->K2mu2e
- B->K6mu
all with identical TightCut requirement: each track in theta/eta acceptance and P>1.85 GeV.