Add summary stats (numbers of nodes, edges, entities etc)

[albertocottica]

Connected to #2 . When the graph regenerates, often the number of entities handled goes up.

[albertocottica]

I see that work was done here. Thanks @jason-vallet !

I would like to have the same on all graphs and edits. For example, when reducing the code co-occurrence graph, it is useful to know what you are reducing it to. Knowing, for example, that if I set the minimum number of co-occurrences to 5, I will be left with a graph with 86 nodes and 212 edges. Same thing for the social network graph: we know we have a certain number of users, but the edges are not entities like posts and comments, they need to be created by the code and then counted.