Feature/api/close-line-algo

[drudilorenzo]

Add algorithms to close the resulting segmentation when it is not already closed after the resulting process.
It is a common behavior with the average class algorithms and with STAPLE when the number of segments is small (less than 8/10).

Implemented methods:

1. Chan Vese
2. Geodesic Active Contour
3. No closing
4. Shape-Preserving Piecewise Cubic Hermite interpolation (PCHIP)

Close #32