Changed to using of UPtrList<Type> instead of List<*Type> for storing
reference to size and velocity groups, as this removes de-referencing
clutter. Fixed lookup of critical film thickness in PrinceBlanch
coalescence model. Added functionality calculating the overall diameter,
void fraction and void fraction weighted velocity for multiple velocity
groups.
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum
Dresden - Rossendorf (HZDR)
739b9e32fb