[Common] add deconvolution of b, nancestor

[ddobrigk]

• adds the possibility of unfolding impact parameter to determine a 'centrality resolution' defined as the ability to determine a sharp impact parameter selection (n.b.: an imperfect definition)
• adds the possibility of unfolding $N_{ancestors}$ in order to have a $N_{ch}/N_{ancestor}$ calculation viable for first-order multiplicity fluctuation bias (using the very, very simplified glauber+NBD machinery)

Tagging @jesgum