Fix unique nodes

[ErinvanderVeen]

Pass -Ofast for more accurate benchmark
Solves #63

[ErinvanderVeen]

SERIAL:

Games/s: 0.38
AI wins: 86.96%
Draws: 1
AI:
    Start Depth: 1
    Average Reached Depth: 21
    Nodes/s: 150869.729066
    Branches: 358417779
    Branches explored: 171976881
    Branches pruned: 186440898
    Branch factor: 2.083014
    % Pruned: 52.017759
    Nodes considered: 172066926
    Nodes evaluated: 48488866
    Unique nodes evaluated: 48488866
    % Unique nodes : 100.000000
HASHMAP:
    Total Hits: 30531681
    Total Misses: 190026796
    % Hit: 13.842896

[ErinvanderVeen]

PARALLEL:

Number of Threads: 2
Games/s: 0.35
AI wins: 80.95%
Draws: 1
AI:
    Start Depth: 1
    Average Reached Depth: 20
    Nodes/s: 392672.915394
    Branches: 425483646
    Branches explored: 218411043
    Branches pruned: 207072603
    Branch factor: 1.946394
    % Pruned: 48.667582
    Nodes considered: 218601012
    Nodes evaluated: 59307875
    Unique nodes evaluated: 43882338
    % Unique nodes : 73.990744
HASHMAP:
    Total Hits: 48716009
    Total Misses: 229368563
    % Hit: 17.518415