GeneXproTools allows you to change both the training and validation/test datasets.
The Add Dataset functionality only applies to the validation/test dataset, as GeneXproTools
must always have a training dataset.
The Change Dataset functionality is important for changing both the training and
validation/test datasets. Changing the training dataset might be important for
refreshing models with new data. On the other hand, changing the validation/test dataset
might be important not only for refreshing old models but also for loading
one or more hold-out datasets for testing.