Save graph to file

[dalek-who]

Currentlt cog only provides APIs for loading graph from file like load_csv , load_triples , load_edgelist , can you provide corresponding APIs for saving, like save_csv , save_triples , save_edgelist ?

[arun1729]

I think these can be added. save_triples and save_edge_list should be straight forward because inherently they are both ways to represent graphs. But save_csv would need a bit more thought.

[arun1729]

#36 #37