ENH: Added new scaledFixedValue boundary condition

Adds new scaledFixedValue boundary condition

This condition applies a scalar multiplier to the value of another boundary condition.

Usage Property | Description | Required | Default value scale | Time varing scale | yes | patch | patchField providing the raw patch value | yes |

Example of the boundary condition specification to scale a reference velocity of (15 0 0) supplied as a fixedValue by a table of values that ramps the scale from 0 to 1 over 1 second:

    <patchName>
    {
        type            scaledFixedValue;

        scale table
        (
            (    0   0)
            (  1.0 1.0)
            (100.0 1.0)
        );

        patch
        {
            type            fixedValue;
            value           uniform (15 0 0);
        }
    }