Replace "MDML" with "MDL"

[Francisco Javier Díez]

One of the metrics that OpenMarkov offers for the hill climbing algorithm is “MDLM”, which stands for “minimum description length metric”. I propose replacing “MDLM” with “MDL”, which is the standard name for this metric.

(I’m proposing this because one of our students tried to find information about the metric “MDLM” on Internet and he found nothing.)