PVC/SKYRAD/M1 - IRT scale factor

The IRT was replaced with a unit with the wrong analog output configuration, such that the 
sky temperature was below the measurable range, resulting in a constant output of 0 
volts or 173.2 K.

• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra-Red Temperature Minima(sky_ir_temp_min)
• Sky infrared temperature, standard deviation(sky_ir_temp_std)
• Sky Infra-Red Temperature(sky_ir_temp)

• Instantaneous Sky/Cloud Infrared(inst_sky_ir_signal)