Small cleanup. Use fxHash instead

[TrevorHansen]

• Uses fxhash to store the costs,
• Takes similar time or is slightly faster,
• Gives the same results,
• Renames the file containing the faster greedy dag extractor

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greedy-dag vs greedy-dag-old

extractors: ['greedy-dag', 'greedy-dag-old']
cumulative time for greedy-dag: 33521ms
cumulative time for greedy-dag-old: 36672ms
cumulative tree cost for greedy-dag: 32017750408986
cumulative tree cost for greedy-dag-old: 32017750408986
cumulative dag cost for greedy-dag: 76907
cumulative dag cost for greedy-dag-old: 76907
Cumulative time for greedy-dag: 33521ms
Cumulative time for greedy-dag-old: 36672ms
greedy-dag / greedy-dag-old
geo mean
tree: 1.0000
dag: 1.0000
micros: 0.9384
quantiles
tree:   1.0000, 1.0000, 1.0000, 1.0000, 1.0000
dag:    1.0000, 1.0000, 1.0000, 1.0000, 1.0000
micros: 0.3897, 0.8423, 0.9043, 1.0635, 2.1116

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bottom-up vs bottom-up-old

extractors: ['bottom-up', 'bottom-up-old']
cumulative time for bottom-up: 3437ms
cumulative time for bottom-up-old: 4349ms
cumulative tree cost for bottom-up: 18584377265237
cumulative tree cost for bottom-up-old: 18584377265237
cumulative dag cost for bottom-up: 77915
cumulative dag cost for bottom-up-old: 77915
Cumulative time for bottom-up: 3437ms
Cumulative time for bottom-up-old: 4349ms
bottom-up / bottom-up-old
geo mean
tree: 1.0000
dag: 1.0000
micros: 0.7792
quantiles
tree:   1.0000, 1.0000, 1.0000, 1.0000, 1.0000
dag:    1.0000, 1.0000, 1.0000, 1.0000, 1.0000
micros: 0.2834, 0.6136, 0.8002, 0.8825, 2.8000

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faster-greedy-dag vs faster-greedy-dag-old

extractors: ['faster-greedy-dag', 'faster-greedy-dag-old']
cumulative time for faster-greedy-dag: 2945ms
cumulative time for faster-greedy-dag-old: 2936ms
cumulative tree cost for faster-greedy-dag: 32017750409008
cumulative tree cost for faster-greedy-dag-old: 32017750409008
cumulative dag cost for faster-greedy-dag: 77029
cumulative dag cost for faster-greedy-dag-old: 77029
Cumulative time for faster-greedy-dag: 2945ms
Cumulative time for faster-greedy-dag-old: 2936ms
faster-greedy-dag / faster-greedy-dag-old
geo mean
tree: 1.0000
dag: 1.0000
micros: 1.0002
quantiles
tree:   1.0000, 1.0000, 1.0000, 1.0000, 1.0000
dag:    1.0000, 1.0000, 1.0000, 1.0000, 1.0000
micros: 0.3750, 0.9367, 0.9969, 1.0209, 2.0588

###################################################
faster-bottom-up vs faster-bottom-up-old

extractors: ['faster-bottom-up', 'faster-bottom-up-old']
cumulative time for faster-bottom-up: 1493ms
cumulative time for faster-bottom-up-old: 1565ms
cumulative tree cost for faster-bottom-up: 18584377265237
cumulative tree cost for faster-bottom-up-old: 18584377265237
cumulative dag cost for faster-bottom-up: 78037
cumulative dag cost for faster-bottom-up-old: 78037
Cumulative time for faster-bottom-up: 1493ms
Cumulative time for faster-bottom-up-old: 1565ms
faster-bottom-up / faster-bottom-up-old
geo mean
tree: 1.0000
dag: 1.0000
micros: 0.9543
quantiles
tree:   1.0000, 1.0000, 1.0000, 1.0000, 1.0000
dag:    1.0000, 1.0000, 1.0000, 1.0000, 1.0000
micros: 0.4363, 0.5649, 1.0049, 1.0951, 2.8000