Add new B0 -> 4pi phase space CP model: LHCBGAUSS-1614
For details, see Jira ticket LHCBGAUSS-1614
To also merge into master and sim09-upgrade branches at some point.
Edited by Gloria Corti
For details, see Jira ticket LHCBGAUSS-1614
To also merge into master and sim09-upgrade branches at some point.