First implementation on tau->3mu skim.

Usage:
cmsrel CMSSW_10_2_18
cd CMSSW_10_2_18/src
cmsenv
git clone https://github.com/rvenditti/Tau3Mu_MiniAOD .
scram b -j20

Skimmer+Ntuplizer sequences can be run with the config files in SkimTools/SkimX/test/ where X=Tau3Mu, PhiPi
Ntuplizer plugins are: DsPhiPiTreeMakerMINI and MiniAnaTau3Mu

TO BE FIXED
- GenParticle info