Merge pull request #5 from homeostasie/dev

Ray intersection
Implémentation de la fonction dray
Test de l'intersection entre le rayon et un cercle.
minor update on comments.
Update README.md
Merge remote-tracking branch 'tl/dev' into circleCompleted
Fixing type and initialisation on circle - ray
adding a method returning a vertex of the convex hull of the digital circle
Merge remote-tracking branch 'tl/dev' into circleCompleted
new class convex hull and its basic test