Reimplemented Suurballe class.

- The new version is the specialized version of CapacityScaling.
- It is about 10-20 times faster than the former Suurballe algorithm
and about 20-50 percent faster than CapacityScaling.
- Doc improvements.
- The test file is also replaced.

 c LEMON max flow problem

 p max 7 9

 n 1 s

 n 7 t

 a 1 2 3

 a 1 3 2

 a 1 4 1

 a 2 5 3

 a 3 5 2

 a 3 7 5

 a 3 6 3

 a 4 6 1

 a 5 7 2

 a 6 7 4