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

Updated noise fft handling via fftw

See merge request OpenFOAM-plus!186

The characteristics of the base scheme are recovered by applying an
explicit correction to the upwind scheme weights.

Usage
    Example of the \c deferredCorrection scheme applied to the \c linear
    scheme:
    \verbatim
    divSchemes
    {
        .
        .
        div(phi,U)      Gauss deferredCorrection linear;
        .
        .
    }
    \endverbatim

Based on a generalised form of a deferred correction linear scheme
supplied by CFD Software E+F GmbH

     avoid unphysical 'fixedValue' at boundaries