Remove "OD" in the root of a strategy tree (method pruneAndGraftNode)

[Manuel Luque]

Method

public void pruneAndGraftNode(String variableName)

of the class

org.openmarkov.core.model.network.potential.treeadd.TreeADDPotential

should remove node "OD" in the root of the strategy tree obtained for the attached network, when unicriterizing with scale value -1 for criterion "Cost".

[Manuel Arias]

Small change to include the case that the root of the tree can also contain the variable that has to be removed.

[Manuel Luque]

Please, mark this issue as "solved" after the corresponding "commit + push" operations, not before... Thanks...