An error was found: the linear regression returns the regression coefficient r, not r2!! It has been modified so that it returns |r| and prints r2 in the info strings.

The HNW_SNOW spatial interpolation algorithm had errors. It was not properly calling its base algorithm (the one computing the initial distribution) and its rating was too low. It has now the same rating as CST_LAPSE for one station when the lapse rate is provided. This could be improved in the future, to make it depend on the rating of the base algorithm...