Triangulate vertices on a sphere

Triangulate a set of vertices on a sphere

Triangulate a set of points on the unit sphere using idea of stereographical projection.

Steps:

1. use the first vertex as projection center, project all the points onto a plane
2. call delaunay triangulation to triangulate those points on the plane
3. fill the hole by connecting the first vertex to the convex hull of the other vertices in the plane

Proof: ? not yet