script_filter (Imlib2::Image)

    /*
     * Apply a scripted filter
     *
     * You should probably using Imlib2::Image#filter() instead, since it is
     * polymorphic (eg, it can handle both static and scripted filters).
     *
     * Example:
     *   x, y = 20, 10
     *   filter_string = "tint( x=#{x}, y=#{y}, red=255, alpha=55 );"
     *   image.script_filter filter_string
     *
     */
    static VALUE image_script_filter(VALUE self, VALUE filter) {