windIO was missing something that went wrong in an earlier merge in the original prepost repository

wetb/prepost/windIO.py

@@ -96,6 +96,10 @@ class LoadResults:
                 ch_dict[tag]['units']
 
     """
+    # ch_df columns, these are created by LoadResults._unified_channel_names
+    cols = set(['bearing_name', 'sensortag', 'bodyname', 'chi', 'component',
+                'pos', 'coord', 'sensortype', 'radius', 'blade_nr', 'units',
+                'output_type', 'io_nr', 'io', 'dll', 'azimuth', 'flap_nr'])
 
     # start with reading the .sel file, containing the info regarding
     # how to read the binary file and the channel information