the kamada_kawai_layout too slow

[ziedbouf]

GPnet/GPnet.py

Line 207 in a0a8a71

self.plot_pos = nx.kamada_kawai_layout(self.Graph)

the kamada_kawai_layout is to slow specially if we want to run on big Dataframe where we need to generate estimation for each row. Done some measurement and found out that the biggest chunk of script goes in the kamada_kawai_layout. It will better to pass one time the kamada_kawai_layout in the initialisation process. I made some changes to the script and i will package things in pull request as soon as i got the chance.