Evolves an electrical potential equation

    \f[
        \grad \left( \sigma \grad V \right)
    \f]

    where \f$ V \f$ is electrical potential and \f$\sigma\f$ is the
    electrical current

    To provide a Joule heating contribution according to:

    Differential form of Joule heating - power per unit volume:

    \f[
        \frac{d(P)}{d(V)} = J \cdot E
    \f]

    where \f$ J \f$ is the current density and \f$ E \f$ the electric
field.
    If no magnetic field is present:

    \f[
        J = \sigma E
    \f]

    The electric field given by

    \f[
        E = \grad V
    \f]

    Therefore:

    \f[
        \frac{d(P)}{d(V)} = J \cdot E
                          = (sigma E) \cdot E
                          = (sigma \grad V) \cdot \grad V
    \f]

Usage
    Isotropic (scalar) electrical conductivity
    \verbatim
    jouleHeatingSourceCoeffs
    {
        anisotropicElectricalConductivity no;

        // Optionally specify the conductivity as a function of
        // temperature
        // Note: if not supplied, this will be read from the time
        // directory
        sigma           table
        (
            (273        1e5)
            (1000       1e5)
        );
    }
    \endverbatim

    Anisotropic (vectorial) electrical conductivity
    jouleHeatingSourceCoeffs
    {
        anisotropicElectricalConductivity yes;

        coordinateSystem
        {
            type        cartesian;
            origin      (0 0 0);

            coordinateRotation
            {
                type        axesRotation;
                e1          (1 0 0);
                e3          (0 0 1);
            }
        }

        // Optionally specify sigma as a function of temperature
        //sigma           (31900 63800 127600);
        //
        //sigma           table
        //(
        //    (0      (0 0 0))
        //    (1000   (127600 127600 127600))
        //);
    }

    Where:
    \table
        Property     | Description               | Required  | Default
value
        T            | Name of temperature field | no        | T
        sigma        | Electrical conductivity as a function of
temperature |no|
        anisotropicElectricalConductivity | Anisotropic flag | yes |
    \endtable

    The electrical conductivity can be specified using either:
    - If the \c sigma entry is present the electrical conductivity is
      specified
      as a function of temperature using a Function1 type
    - If not present the sigma field will be read from file
    - If the anisotropicElectricalConductivity flag is set to 'true',
      sigma
      should be specified as a vector quantity

Updating fvSolution's for closed domains for chtMultiRegionFoam cases

simpleRho or limiting p.

Update pEq for close domains.

2)Adapting divU in TEqn.H for compressibleInterDyMFoam and compressibleInterFoam
3)Re-instated sixDoFRigidBodyDisplacement as patch for pointFields. It allows to use a different fvDynamincMesh type
independently of the BC's

- these are compile-time constants and can be marked as such in C++11.

Modification on rhoPimpleFoam pEq's for handling rho thermo and incompressible EoS. Adding rho limiters if p is limited.
This is important when LTS stepping or large Co number is used.

Updating rhoBuoyantPimpleFoam to handle closed domain for rho thermo and incompressible Eos.
Consolidating chtMultiRegionSimpleFoam and chtMultiRegionFoam pEqs to use the same formulation as rhoBuoyantPimpleFoam and
rhoBuoyantSimpleFoam

ENH: noiseModels - updated parallel usage (no longer needs proc dirs) and apply input data validation

Revert "sixDoFRigidBodyDisplacementPointPatchVectorField, uncoupledSixDoFRigidBodyDisplacementPointPatchVectorField: removed"

This reverts commit 942338b0.

COMP: unitConversion - using M_PI instead of pi to avoid compiltion error due to pi not evaluating to a constexpr

Feature surface feature extract

See merge request !110

ccm conversion bugfixes

See merge request !115

- was generally somewhat fragile. The main problem stems from the fact
  that several interfaces may be attached to a boundary. No trivial
  means of solving this without too much work for a feature that is only
  "nice-to-have".