Adapt configure to accept unconnected tf trees

[brunofavs]

ATOM should look if all the chains between the estimated tf's and not the entire tree.

In zau there were multiple tf branches that we discarded but were bugging our configure.

atom/atom_calibration/scripts/configure_calibration_pkg

Lines 418 to 426 in a57f165

	if nx.is_weakly_connected(nx_graph):
	print('Checking if TF tree is connected ... ', end='')
	else:
	pos = nx.random_layout(nx_graph)
	edges, weights = zip(*nx.get_edge_attributes(nx_graph, 'weight').items())
	# edge_labels = nx.draw_networkx_edge_labels(nx_graph, pos)
	nx.draw(nx_graph, with_labels=True)
	plt.show()
	raise ValueError('TF tree is not connected. Aborting.')

[miguelriemoliveira]

This may have many implications. Will give it low priority for now...