sortByCriterion: Sorting results of a [Mixmod] object by a given criterion
Description
After calling the mixmodCluster() or mixmodLearn() method, results will be sorted
into ascending order according to the first given criterion (descending order for CV criterion).
This method is able to reorder the list of results according to a given criterion.
Usage
sortByCriterion(object, criterion)
# S4 method for Mixmod,character
sortByCriterion(object, criterion)