laminarFlameSpeed: Extended interface

to provide access to the lower lever laminar flame speed functions of the pressure, temperature, equivalence ration and optional EGR mass fraction:

// Member Functions

    //- Return the laminar flame speed [m/s]
    virtual tmp<volScalarField> Su
    (
        const volScalarField& p,
        const volScalarField& Tu,
        const volScalarField& Phi
    ) const = 0;

    //- Return the laminar flame speed [m/s]
    //  including EGR effects
    virtual tmp<volScalarField> Su
    (
        const volScalarField& p,
        const volScalarField& Tu,
        const volScalarField& Phi,
        const volScalarField& egr
    ) const = 0;

    //- Return the laminar flame speed [m/s]
    //  assuming a single fuel specie
    virtual tmp<volScalarField> Su() const;