ENH: Adding interCondensingEvaporatingFoam and tutorial

Solver for 2 incompressible, isothermal immiscible fluids using a VOF
(volume of fluid) phase-fraction based interface capturing approach.
The momentum and other fluid properties are of the "mixture" and a single
momentum equation is solved.

Solver: /applications/solvers/multiphase/interCondensingEvaporatingFoam Tutorial: /tutorials/multiphase/interCondensingEvaporatingFoam/condensatingVessel