seasonal multimodel developed. pooled works for both deterministic and probabilistic forecasts. for mean and median approaches, deterministic multimodel works and probabilistic multimodel is not correct (need to adjust the probabilities computation)

Changes for changed decadal data path and structure

See merge request !56

Avoid producing Inf when all data are NAs

See merge request !109

Tas-tos data blending development

See merge request es/sunset!102