Reduction Rules 1-5

1. Loop deletion
2. Split into strong components (@phaker)
   • Tarjan's algorithm petgraph::algo::tarjan_scc
3. In neighbor shortcut (@ken_die)
4. Out neighbor shortcut (@ken_die)
5. Two disjoint Cycles (@ken_die)
   • Implement and test Karger min-cut
   • Implement and test Stör min-cut
   • Implement and test Edmonds-Karp min-cut