Init Algorithms (add stdlib and algs4)
PA1: Add file loading in WordNet
PA1: Add SAP (Shortest Ancestral Path)
PA1: Add Outcast (incorrect parallel BFS algorithm)
PA1: Correct twice BFS algorithm (out of time)

1. Immutable class SAP.
PA1: Speedup file loading
Fixed a bug of algs4
PA2: Add SeamCarver (out of time)

Using EdgeWeightedDigraph and AcyclicSP
PA2: Speedup (DP)
Add a reference