added Eliahou graph (#26)
added Eliahou graph (#26)

* new sonstree more flexible

Also example of tree of Arf numerical semigroups

* added oversemigroups

draws over semigroups, irreducibles go as diamonds

* added Eliahou graph

* added Rosales' graphs

also renamed Eliahou’ graph -> Draw…

mcmartins/francy,mcmartins/francy,mcmartins/francy,mcmartins/francy