Rename min mean cycle classes and their members (#179)
with respect to the possible introduction of min ratio
cycle algorithms in the future.

The renamed classes:
- Karp --> KarpMmc
- HartmannOrlin --> HartmannOrlinMmc
- Howard --> HowardMmc

The renamed members:
- cycleLength() --> cycleCost()
- cycleArcNum() --> cycleSize()
- findMinMean() --> findCycleMean()
- Value --> Cost
- LargeValue --> LargeCost
- SetLargeValue --> SetLargeCost

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 2 	3 	6 	  10

 2 	4 	7 	  8

 2 	6 	8 	  8

 5 	3 	9 	  20

 3 	6 	10 	  25

 4 	7 	11 	  15

 5 	7 	12 	  15

 6 	7 	13 	  18

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