NSA/SKYRAD/C2 - Incorrect 20s dome thermistor data

The 30-second and 50-second PIR2 diffuse dome thermistor data
in all skyrad 20s data records taken to data is in fact case
thermistor data.  No other data are affected.  The 20 second
skyrad data cannot be used to recompute the diffuse PIR2 data.

Note: This data was named pir2_dome_therm at the beginning of
this time range and later the variable was renamed to
inst_down_long_shaded2_dome_resist.

• Instantaneous PIR2 dome thermistor(pir2_dome_therm)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Shaded
  Pyrgeometer2(inst_down_long_shaded2_dome_resist)