quantiles study, analysisOnGen->python3

[vberta]

In this PR is present

1. the porting of analysisOnGen to python3.

2. the scripts for quantile binning study.

• The study is fully reproducible running analysisOnGen with a very-fine binning in qt-Y (0.1 GeV, 0.1 in Y binning in the all the kinematic range). Otherwise this file can be used:
  /scratch/bertacch/wmass/wproperties-analysis/analysisOnGen/GenInfo/genInfo_fine4quantiles.root
• The proper lines are left commented in analysisOnGen to reproduce this file.
• the results are reported as documentation inside "quantileBinBuilder" script.
• the result for qt binning is already implemented in C++ modules of analysisOnGen.
• the central value is NOT implemented. it must be changed in the future where needed.
• the file: /scratch/bertacch/wmass/wproperties-analysis/analysisOnGen/scripts/quantileBinBuilder.root contains the quantiles study output plots.