Iterative Longest Path Layerer

[Eddykasp]

An iterative version of the longest path layerer to adress #872. There is no longer a Stackoverflow exception for the example graph, however, the layout still takes too long with this version. The existing recursive version may be good enough for typical problems.

[Eddykasp]

In BinaryIndexedTree in the rank method an IndexOutOfBoundsError now occurs with this example graph. Other tests are still passing.