Add ΔR variables.
Add true vertex count.
Make the tau event veto optional (and activate it).
Simplify lepton veto requirements.  We can't have both at once.
Add a new TL channel.

Main objective is too see if we can get the jet fake rate from
Z→ττ→lepton+hadronic τ.
Add MET covariance matrix.
Add Lorentz vectors for taus, leptons.