Comment 1 for bug 372740

igraph_get_all_shortest_paths now supports a `to` argument (implemented by Gabor). Added some checks to ensure that we don't keep on searching if we reached all the target nodes. This speeds up things a lot if the graph is highly regular (i.e., 100 x 100 lattice and we are looking for a shortest path between node (0, 0) and node (2, 2)).