Merge pull request alisw#191 from fprino/master

Modified printout of error message

Merge pull request alisw#180 from qgp/update_doc

Update PWG-MM README

Checkpoint history rewrite

CaloPhotonCuts: tune NL params

few fixes & additions here and there...

check ratio Ecell lead over E cluster vs number of local maxima

User-settable TF1 for mass mean, sigma (which then avoids initial fit…

… to ensure speed + stability)

added support for 'hybrid approach'

Bug Fix in Histogram

Change to THnSparse

3D histograms in this task expected to be sparsely filled,
in particular for min. bias events. In this case THnSparse
is more efficient in memory consumption compared to a TH3.