Provide a bridge to PyGOBN

[smarie]

From PyGOBN doc:

>>> gobn = GOBN()
>>> edge_reqs = {'A':['B','C'],'B':['D']} # require that A->B, A->C, and B->D
>>> ind_reqs = [('A','D'),(('A','B'),'D','C')] # require that A _|_ D and A,B _|_ D | C
>>> nonedge_reqs = {'B':['C']} # disallow that B->C
>>> gobn.set_constraints(edge_reqs, ind_reqs, nonedge_reqs)
>>> gobn.learn(data) # Call the GOBNILP solver

So we can maybe provide a <QDForest>.to_pygobn() method that would return a tuple edge_reqs, ind_reqs, and nonedge_reqs. The user would therefore do:

from qdscreeen import qdeterscreen
from pyGOBN import GOBN

# screen for (quasi-)determinism and get the contraints to pass to GOBN
qd_forest = qdeterscreen(data[, options])
reqs = qd_forest.to_pygobn()

# run GOBN with these constraints
gobn = GOBN()
gobn.set_constraints(*reqs)
gobn.learn(data)