TWP/SKYRAD/C3 - Reprocess: PIR identified as unshaded is really shaded

From the initial installation of the Dqrwin SKYRAD
suite if instruments, two shaded PIRs were installed
rather than one shaded and one unshaded PIR as 
documented in the netcdf header information.

See P011109.2 for more discussion of this issue.

Disregard the data description in the netcf header

• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_unshaded_std)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)