Finally, another method for handling daily sums of solar radiation has been implemented: when a point is requested, the potential solar radiation is computed for the whole day with a 20 minutes resolution, filling a vector and computing the daily sum. This enables to compute the loss factor. When another point within the same day is requested, the radiation is interpolated from the values stored in the vector and multiplied by the loss factor. Tested on WFJ data, this works very well (of course, days that experience large cloudiness variations are not reproduced well but at least the average flux is correct).

A typo has been fixed in the documentation of Date.