1) Introduction of ncores as extra parameter. 2) Introduction of Calibration as a new function (replacement of .calibration.wrap). 3) removal of var.fc

Handling of case of insufficient data, following the comment of Deborah Verfaillie. The function now warns (and does no calibration) when 3 or less observation-model pairs are available for training. A new parameter na.fill has been introduced.

1) function name CST_CategFc replaced with CST_CategoricalEnsCombination. 2) Additional dimension named member of size 1 added to output object to make it compatible with s2dv_cube requirements, 3) test function introduced with multiple tests, including test for dimension sizes and names, 4) documentation in CST_CategoricalEnsCombination adapted to change 2.