switch

The new lowReCorrection entry can be used to ensure that the low-Re
mode is only applied when its value is on/true, e.g.

    lowReCorrection      on;

When active, the low-Re mode is active when the local y+ is less than
the calculated y+_laminar.  When inactive, the high-Re form is employed
irrespectively of the local y+.

It has a defaulrt value of off/false for backwards compatibility with
OpenFOAM v1706

BUG: Fixing creating of turbulence after overset specific in createFields.H for overRhoPimpleDyMFoam

Computes the heat transfer coefficient [W/m2/K] using a run-time
selectable model:
- ReynoldsAnalogy
- fixedReferenceTemperature
- localReferenceTemperature

- was using system/decomposeParDict and ignoring the command-line
  option.

further investigation on the consequences on dynamic mesh for compressibleInterDyMFoam.
alphaSuSp.H has to be added in the solver folder in order to make it compatible with the alpha Eq.

Fixing fvOption in multiphase/reactingTwoPhaseEulerFoam/laminar/steamInjection

NOTE: The radiative flux (qr) is positive when the heat flux is going into the wall,
this is oposite the the he flux which is positive going out of the wall.

- removed some unneeded tutorial files

- add some notes about 'git submodule' in modules/README.md