Switch GPS east west position

If your precious GPS tracker gets confused by east west and your exif info positions your fotos into the lybian desert instead of the canaries:

C:\Tools\exiftool>exiftool -ext .jpg -overwrite_original_in_place -P -r -GPSLongitudeRef=W z:\2015\Teneriffa2015\

This should overwrite all east with west positions.