Latent heat evaluation has been changed to calculate both sides' heats
similarly using the interface temperature, rather than using bulk
quantities on the "upwind" side of the mass transfer process
(latentHeatScheme::symmetric vs latentHeatScheme::upwind).
The transfer of heat has been changed so that it is calculated from the
mass transfer rate rather than the heat transfer coefficients and
temperatures (latentHeatTransfer::mass vs latentHeatTransfer::heat).
These changes were found to improve stability characteristics in some
boiling cases, and in general should be more energy conservative and
less dependent on the accuracy of the interfacial temeprature solution.
Patch contributed by Juho Peltola, VTT.