Change the default configuration of the "WupPer" argument (SimGR and CalGR functions)

No matter if the "WupPer" argument is (i) not defined, (ii) equal to NULL or (iii) equal to 0L, a default configuration is applied to the model warm up period, namely the year preceding the run period is used. Thus, it is impossible to perform a simulation without model warm-up.

Is it possible to change this default configuration as for airGR?