and two-phase functionality separated from multiphase functionality

Multi-species, mass-transfer and reaction support and multi-phase
structure provided by William Bainbridge.

Integration of the latest p-U and face-p_U algorithms with William's
multi-phase structure is not quite complete due to design
incompatibilities which needs further development.  However the
integration of the functionality is complete.

The results of the tutorials are not exactly the same for the
twoPhaseEulerFoam and reactingTwoPhaseEulerFoam solvers but are very
similar.  Further analysis in needed to ensure these differences are
physical or to resolve them; in the meantime the twoPhaseEulerFoam
solver will be maintained.

This reverts commit c5bea524.

This reverts commit b18f6cc1.

Exception: applyWallFunctionBoundaryConditions.C cannot split #include
directives.

avoid name-clashes with the standard viscosityModels.

The other kineticTheoryModels have yet to be put in the kineticTheoryModels
namespace.

avoid name-clashes with the standard viscosityModels.

The other kineticTheoryModels have yet to be put in the kineticTheoryModels
namespace.