Betweeness centrality has been removed : it was making things much slower and wasn't needed right now. We will enable it when we need it
main.ccp has been split into 3 files :
    graph.cpp for graph generation and manipulation
    results.cpp to gather the results of the simulation
    main.cpp to launch the simulation and display the results

Adding propagation.py, not functionnal yet

Conflicts:
	main.py

    The connections who had failed are now removed correctly from connection_dict

This information is passed to the application

    server and client log file are now opened in WRONLY mode instead of RDONLY
    connections are not refreshed evrytime that a message is transmited on the pipe
Open vpn now trigger client-disconnect
When a new client arrive, its IP is sent to the pipe

Conflicts:
	main.py

Conflicts:
	main.py

Vifibnet now establish a few random connection from a list a given peers and change some evry 2 minutes