If one of "sonic_h2o_separation_corrected", "sonic_co2_separation_corrected",
or "gsoil_philip_corrected" are not found in the netcdf, set them to NULL in dpar().
Updates to weight handling code in average of 2nd order moments.
When weights differ, NA the data and set the weights to 0.
Also the weightmap of the component values was being lost and so the
weights were not being used in those averages.
Added corrected weights handling to averaging of 3rd order moments.