Add graph references

references/igraph-1.0.1/tests/unit/igraph_diameter.out

@@ -0,0 +1,17 @@
+diameter of Barabasi graph:
+Diameter: 2
+diameter of ring and the path in terms of edges and vertices 
+diameter: 9, from 0 to 9
+( 0 1 2 3 4 5 6 7 8 9 )
+( 0 1 2 3 4 5 6 7 8 )
+disconnected ring graph
+The largest path in one connected component
+5
+uconn = False 
+Inf
+graph with zero nodes
+NaN
+from = -1, to = -1
+graph with one node
+0
+from = 0, to = 0