Topological Ordering Output

[Malte311]

Output a topological ordering instead of the extended graph. Use an extra function for computing the extended graph from the ordering. This allows separate time measurements.

Another advantage of this is that filter can be used to direct all edges in one step which should be faster than directing each edge on its own.

[Malte311]

Implemented this and it was slower than the old version, so i moved back to the old version.

(changes were reverted in e7235c3)