Adding poly solid thermo to InterfaceCompositionModel for use
on icoReactingMultiphaseInterFoam

See #1328.

Based on Goring et al., 1980

- no use having wmkdepend on the target architecture when it will only
  be needed on the host architecture.

- remove make target for wmdep (flex-based scanner), which eliminates
  a bootstrap dependency on flex.

  As of OpenFOAM-v1806, wmdep has been superseded by wmdepend
  (ragel-based scanner).

- replace dirToString binary with shell/awk equivalent for simpler
  maintenance. The utility is very rarely used (auto scanning to
  create Make/files) so there is no performance difference.

Feature vof update solvers

See merge request OpenFOAM-plus!266

Integration of VOF MULES new interfaces. Update of VOF solvers and all instances
of MULES in the code.
Integration of reactingTwoPhaseEuler and reactingMultiphaseEuler solvers and sub-models
Updating reactingEuler tutorials accordingly (most of them tested)

New eRefConst thermo used in tutorials. Some modifications at thermo specie level
affecting mostly eThermo. hThermo mostly unaffected

New chtMultiRegionTwoPhaseEulerFoam solver for quenching and tutorial.

Phases sub-models for reactingTwoPhaseEuler and reactingMultiphaseEuler were moved
to src/phaseSystemModels/reactingEulerFoam in order to be used by BC for
chtMultiRegionTwoPhaseEulerFoam.

Update of interCondensatingEvaporatingFoam solver.

- if surface is only on a single processor, no point merging occurs
  and the pointsMap is empty.

- overload the ref() method to allow modification of the referenced
  (non-const) field directly. Same as constCast(), but less typing
  and less prone to error.

- construct ConstPrecisionAdaptor from tmp for improved efficiency.

- the updated surface writers must be explicitly tagged as being
  Time-aware (useTimeDir) to have them splice Time (in this case freq)
  into the output path.

  The older writers worked in the opposite way. They extracted a time
  value from the naming of the output directory (which was fragile).

Feature single precision

See merge request OpenFOAM-plus!234