Add option to override the measured intensities by the reflector bit / median bit information

[benmaidel]

As the reflector information from the extended scan (reflector_status, reflector_median) is more reliable for for reflector marker detection, I've add an option to fill the intensity from the default scan message with the info provided in either the reflector_status or reflector_median. This is then kind of a similar behavior as the old sick s300 scan driver had and enables backwards compatibility. As default the drivers behavior is unchanged.