master branch to-do list

[gfasanel]

Hi,
I have few suggestions to have a fully functional master branch

1. Insert back the GetCorrTree method in EnergyScaleCorrection_class
2. The dat file with the corrections will be on /eos/project/.... but at the moment I think the class have some problems in finding a file on eos
3. Small fix in macro/plot_data_mc.C to avoid warnings/errors when compiling (img_filename is not directly used and the output is dumped in a TString)
   https://github.com/ECALELFS/ECALELF/blob/workflow_test/ZFitter/macro/plot_data_mc.C#L277

Cheers,
Giuseppe