[Bug] EdgeDepthFirstSearchAlgorithm does not find multiple paths when the root vertex has parallel edges

[TheDudeCode]

Considering the following graph

For this graph we would like to know all possible paths between two nodes. So for the example below the resulting paths between nodes 0 and 2 would be:

• 0 -> 2
  

• 0 -edge A-> 1 -> 2
  

• 0 -edge B-> 1 -> 2
  

The code to accomplish this is:

var startNode = "0";
var endNode = "2";

var graph = new AdjacencyGraph<string, TaggedEdge<string, string>>(allowParallelEdges: true);

var edges = new List<TaggedEdge<string, string>>{
    new TaggedEdge<string, string>("0", "1", "edge A"),
    new TaggedEdge<string, string>("0", "1", "edge B"),
    new TaggedEdge<string, string>("1", "2", string.Empty),
    new TaggedEdge<string, string>("0", "2", string.Empty),
    new TaggedEdge<string, string>("0", "3", string.Empty),
    new TaggedEdge<string, string>("1", "3", string.Empty), };
edges.ForEach(x => graph.AddVerticesAndEdge(x));

var algo = new EdgeDepthFirstSearchAlgorithm<string, TaggedEdge<string, string>>(graph);
var observer = new EdgePredecessorRecorderObserver<string, TaggedEdge<string, string>>();

using (observer.Attach(algo))
{
    algo.Compute(startNode);
}

var allPaths = observer.AllPaths().Where(x => x.Last().Target == endNode)
```;

However only 2 paths are found, not finding the one that has edge B:
-     0 -> 2
-     0 -edge A-> 1 -> 2

Would we add a parallel edge between nodes 1 and 2, then indeed 3 paths are found.

[KeRNeLith]

Closing because it is a duplicate of #21.