WIP: Feature euler euler solvers. Integration of Euler solvers.

Summary

New chtMultiRegionTwoPhaseEulerFoam solver, plus corresponding BC's Integrated MULES and CMULES new interfaces and the corresponding multiphase solvers multiphase tutorials not tested/updated New library src/phaseSystemModels for all the phases systems, sub-models, BC's, turbulence. This lib was taken out of the Euler solvers and located on /src This branch was not rebased on the latest develop as it needs several more updates first (including headers).

Work to do:

1. Review latest form org for the phases modeling.
2. Review latest tutorial entries

Details of new models (If applicable)

chtMultiRegionTwoPhaseEulerFoam and the extended alphaBoilingWall BC is designed to deal with several cooling regimes:

    single phase
    subcooled nucleate wall boiling
    transitional boiling
    film boiling.

The wall function uses a partition method to transfer heat either
to the liquid or vapor phase. At the moment, this function works
in a wall temperature fixed mode. i.e, there is no consideration
for the sudden change of heat transfer coefficient (htc) after
reaching TDBN (deviation from nucleate boiling temperature)

More details on alphatWallBoilingWallFunctionFvPatchScalarField.C

Risks

Need to test all the multiphase tutorials due to significant changes from the last year and some changes this year from org. This should be done when the merge is completed.