Improves stability and convergence of systems in which drag dominates
e.g. small particles in high-speed gas flow.

Additionally a new ddtPhiCorr strategy is included in which correction
is applied only where the phases are nearly pure.  This reduces
staggering patters near the free-surface of bubble-column simulations.

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1421

twoPhaseEulerFoam JohnsonJacksonFrictionalStress: alphaDeltaMax now user input (previously hard-coded to 5e-2)

to avoid excessive pressure/buoyancy balance errors on non-orthogonal meshes
Resolves bug-report http://openfoam.org/mantisbt/view.php?id=1379

Correction provided by Juho Peltola

Resolved bug-report http://www.openfoam.org/mantisbt/view.php?id=1564

Needed to create generic compressible turbulence model library

Resolves bug-report http://openfoam.org/mantisbt/view.php?id=1382

Explicitly name derived fields to improve readability of diagnostic messages and avoid duplicate registration

twoPhaseEulerFoam/twoPhaseSystem/diameterModels/constantDiameter: Do not register the temporary diameter field

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1505

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1402

Currently these vectors are generated at the same time as the wall-distance field
by the same run-time selected algorithm.  This will be changed so that the wall-reflection
vectors are only generated and stored if required.

When using models which require the wallDist e.g. kOmegaSST it will
request the method to be used from the wallDist sub-dictionary in
fvSchemes e.g.

wallDist
{
    method meshWave;
}

specifies the mesh-wave method as hard-coded in previous OpenFOAM versions.

In preparation for run-time selectable methods

to support improved discretisation in pEqn and implicit treatment in the phase-fraction equation

Provided by Juho Peltola