Function1::Scale: New function to scale a given function by a scalar function, e.g. a ramp

For example in the potentialFreeSurfaceFoam/oscillatingBox tutorial it is
cleaner to apply the "linearRamp" function to the "sine" function rather than
using an amplitude table:

    floatingObject
    {
        type            fixedNormalInletOutletVelocity;

        fixTangentialInflow false;

        normalVelocity
        {
            type            uniformFixedValue;

            uniformValue
            {
                type        scale;

                value
                {
                    type sine;

                    frequency   1;
                    amplitude   0.025;
                    scale       (0 1 0);
                    level       (0 0 0);
                }

                scale
                {
                    type linearRamp;

                    duration 10;
                }
            }
        }

        value           uniform (0 0 0);
    }