Output  of Eccentricity

```
Output will be:

A is not in the centroid
B is not in the centroid
C is in the centroid
D is not in the centroid
E is not in the centroid
F is not in the centroid
G is not in the centroid
```
should be moved from https://graphstream-project.org/doc/Algorithms/Eccentricity/
to https://graphstream-project.org/doc/Algorithms/Centroid/