Explicit tests for bipartite graph generators

[szhorvat]

We need explicit tests for:

• [ ] igraph_full_bipartite()
• [x] igraph_bipartite_game_gnm()
• [x] igraph_bipartite_game_gnp()

Do you have time to take this @GroteGnoom ?

[szhorvat]

I see that igraph_bipartite_game() already has a test. Somehow my IDE didn't find that mention of the function.

This test should be refactored to refer to the gnm and gnp versions separately, and should test both the directed and undirected case.

I think we should soon deprecate igraph_bipartite_game() in favour of the explicit G(n,m) / G(n,p) versions, since we also deprecated igraph_erdos_renyi_game(). Any objections to the deprecation, @ntamas ?

[ntamas]

No objections, go ahead.