This was needed for application like postProcess.H in order to force the reading of thermal p on
every time.

This allows single, multi-phase and VoF compressible simulations to be performed
with the accurate thermophysical property functions for liquids provided by the
liquidProperty classes.  e.g. in the
multiphase/compressibleInterFoam/laminar/depthCharge2D tutorial water can now be
specified by

thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    properties      liquid;
    energy          sensibleInternalEnergy;
}

mixture
{
    H2O;
}

as an alternative to the previous less accurate representation defined by

thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState perfectFluid;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        molWeight   18.0;
    }
    equationOfState
    {
        R           3000;
        rho0        1027;
    }
    thermodynamics
    {
        Cp          4195;
        Hf          0;
    }
    transport
    {
        mu          3.645e-4;
        Pr          2.289;
    }
}

However the increase in accuracy of the new simpler and more convenient
specification and representation comes at a cost: the NSRDS functions used by
the liquidProperties classes are relatively expensive to evaluate and the
depthCharge2D case takes ~14% longer to run.

GeometricField: Renamed internalField() -> primitiveField() and dimensionedInternalField() -> internalField()

These new names are more consistent and logical because:

primitiveField():
primitiveFieldRef():
    Provides low-level access to the Field<Type> (primitive field)
    without dimension or mesh-consistency checking.  This should only be
    used in the low-level functions where dimensional consistency is
    ensured by careful programming and computational efficiency is
    paramount.

internalField():
internalFieldRef():
    Provides access to the DimensionedField<Type, GeoMesh> of values on
    the internal mesh-type for which the GeometricField is defined and
    supports dimension and checking and mesh-consistency checking.

When the GeometricBoundaryField template class was originally written it
was a separate class in the Foam namespace rather than a sub-class of
GeometricField as it is now.  Without loss of clarity and simplifying
code which access the boundary field of GeometricFields it is better
that GeometricBoundaryField be renamed Boundary for consistency with the
new naming convention for the type of the dimensioned internal field:
Internal, see commit a25a449c

This is a very simple text substitution change which can be applied to
any code which compiles with the OpenFOAM-dev libraries.

Avoids the clutter and maintenance effort associated with providing the
function signature string.