Updating metrics of diversity to take into account graph structure. This will have to change in the future.

Modified increment for graph, since randomwalk return same vertex as the one provided when niter = 1

we changed the way we store agents in Simulation. Now it is a vector of vector of agents, and it seems to perform much better. Thus we are merging all this in v1.0

now we need to unit test gillepsiee.jl, and especially the update rates
almost there!