DCEL.h

- Added coordinate member to vertex class (was missing)
- Renamed Face class to Region to avoid ambiguities between 2D area of the Voronoid algo and an actual 3D face

main.cpp
- Implemented drawControlPoints and stubbed drawVoronoiDiagram and drawEdges
- Added a set to contain the points.

utils.h
- added the file to contains a vertex wrapper

reviewed by Alex