Arb.h:
- Add a avl tree

main.cpp:
- refactored vertices to sites
- Added call to the VoronoiDiagram class
- moved compareSite to utils.h
- a bit clean up

utils.h:
- moved compareSite from main.cpp

Voronoi .h .cpp:
- Added the file

reviewed by Myriam
Merge branch 'master' of https://github.com/FrancoisBelanger/IMN430