calib_cws() about brassens

[eva0marques]

1. Select all observations in x at less than x meters from a ref station (param option: distance x in meters)
2. Measure the anomaly in temperature for these observations in regard to the ref
3. Compute the average bias (param option: per hour of the day)
4. Remove this bias to all the observations
5. Return obs corrected and the average bias.