=Griffeath's cellulare automaton implementation Author:: Michel Belleville <mailto:michel.belleville@gmail.com> Rules : * cells may evolve cycling through (n) states (4 by default). * first state (0) is a "null" state by convention. * a cell evolve to the next state when at least 3 of its neighbors are already on said next state. * a cell that doesn't evolve remains on the same state.