replace Road and Anchor with Edge (inheriting from RoadView)

[funketh]

• Edge is used instead of Anchor but replaces Road as well
• Edges can only exist as pairs of 2 (one per Vertex) and represent a road
  • data about the road is shared between the 2 Edge objects
• an Edge represents how the road would look like if you were to stand at one of its endpoints (there is one Edge object for each endpoint)
• Since roads are constructed before vertices, there are RoadView objects which are just like Edge objects but they don't have a Vertex assigned to them yet
• Point has now become redundant; Vector2D will be used instead

[funketh]

In der Vertex Klasse wird die pathfinding Methode implementiert sein:

public Path FindPath(Vertex endVertex)
{
    // find path by iterating over self._edges
}

Damit wir halt nicht für jede Section nen eigenes pathfinding implementieren müssen, haben wir den Array an Edges.