Dico reduce in0
Purpose
This merge adds contractions operation in0 on top of loop (removing all vertices having null in-degree), it includes loop since the merge request !25 also introduced some functionalities that are common to other operations.
This merge adds contractions operation in0 on top of loop (removing all vertices having null in-degree), it includes loop since the merge request !25 also introduced some functionalities that are common to other operations.