New lift model supporting near-wall damping using the new
wallDampingModels.

e.g.

lift
(
    (air in water)
    {
        type            wallDamped;
        lift
        {
            type            constantCoefficient;
            Cl              0.5;
        }
        wallDamping
        {
            type            linear;
            Cd              0.5;
        }
    }
);

in which a linear near-wall damping function min(y/(Cd*d), 1) is applied to the constant
coefficient lift model.  Additional wall-damping functions will be added.