Changed the BFS algorithm to return the tree in a vector of levels and
the search for the node at the maximum distance from solution can now be
found easily and much faster.
Graph Class:
- Changed the bfs method and new getShortestPath method (replaces the
previous "bfsPath")
Game Class:
- Changed the search for the node at the maximum distance from solution
to perform a BFS starting from the solution node and get the reverse
path from solution to any node in the last level of the BFS-tree