Provide possibility to represent the Petri net in Graph Viz with an horizontal layout instead of vertical about pm4py-core

[Javert899]

The possibility to set the horizontal layout on Petri net representations has been provided using the pn_vis_factory.RANKDIR_LR parameter, in the 'develop' branch.

The following example code could be used:

from pm4py.objects.log.importer.xes import factory as xes_importer
from pm4py.algo.discovery.inductive import factory as inductive_miner
from pm4py.visualization.petrinet import factory as pn_vis_factory

log = xes_importer.apply("C:\running-example.xes")
net, im, fm = inductive_miner.apply(log)
gviz = pn_vis_factory.apply(net, im, fm, parameters={pn_vis_factory.RANKDIR_LR: True})
pn_vis_factory.view(gviz)