of a compressible single-phase flow

See tutorials/compressible/sonicFoam/laminar/forwardStep/system/controlDict

functionObjects::flowType: new functionObject which calculates and writes the flowType of velocity field

    The flow type parameter is obtained according to the following equation:
    \verbatim
                 |D| - |Omega|
        lambda = -------------
                 |D| + |Omega|

        -1 = rotational flow
         0 = simple shear flow
         1 = planar extensional flow
    \endverbatim

DimensionedScalarField, GeometricScalarField: Added more rigorous dimension-checking for 'pow' functions

to return unchanged 'tmp' arguments

functionObjects::Peclet -> functionObjects::PecletNo for consistency with functionObjects::CourantNo

const-ness of the stored object is checked at run-time.

In most boundary conditions, fvOptions etc. required and optional fields
to be looked-up from the objectRegistry are selected by setting the
keyword corresponding to the standard field name in the BC etc. to the
appropriate name in the objectRegistry.  Usually a default is provided
with sets the field name to the keyword name, e.g. in the
totalPressureFvPatchScalarField the velocity is selected by setting the
keyword 'U' to the appropriate name which defaults to 'U':

        Property     | Description             | Required    | Default value
        U            | velocity field name     | no          | U
        phi          | flux field name         | no          | phi
        .
        .
        .

However, in some BCs and functionObjects and many fvOptions another
convention is used in which the field name keyword is appended by 'Name'
e.g.

        Property     | Description             | Required    | Default value
        pName        | pressure field name     | no          | p
        UName        | velocity field name     | no          | U

This difference in convention is unnecessary and confusing, hinders code
and dictionary reuse and complicates code maintenance.  In this commit
the appended 'Name' is removed from the field selection keywords
standardizing OpenFOAM on the first convention above.

temperatureCoupledBase: Rationalized the selection of the method for obtaining the thermal conductivity

kappa -> kappaMethod
kappaName -> kappa

functionObjects, foamCalcFunctions, fvOptions: Standardized keywords for selecting fields and objects

Generally fields and objects are selected using the 'field[s]' and
'object[s]' keywords but this was not consistent between all
functionObject, fvOptions etc. and now fixed by applying the following
renaming:

fieldName -> field
fieldNames -> fields
objectName -> object
objectNames -> objects

e.g.

functions
{
    libs ("libfieldFunctionObjects.so");

    div
    {
        type            div;
        field           U;
        executeControl  writeTime;
        writeControl    writeTime;
    }

    Q
    {
        type            Q;
        executeControl  writeTime;
        writeControl    writeTime;
    }
}

functionObjects: New abstract base-class 'fieldExpression' for simple field expression evaluation functionObjects
Updated and simplified 'div', 'grad' and 'mag' functionObjects by deriving from 'fieldExpression'.
Corrected the handling of cached gradients in 'grad'.