Suggestion: Example for exact voronoi diagram from Segment_Delaunay_graph_2 for simple polygons for the User Manual

[zsln]

Issue Details

Missing example for exact voronoi diagram extraction from Segment_Delaunay_graph_2. The existing examples only use EPICK or Simple_cartesian Kernels, which will fail on simple configurations I've encountered applying the method.
The example also contains an example implementation for collecting the rays/lines/segments of the voronoi cells. It does not require to have other files necessary for reading.
I think (especially non-CGAL native) people would benefit from the example, as it will most likely work.
It is quite simple as it does not require additional files for data.

Source Code

Here's a gist. I didn't want to fork the whole thing for adding an example to the User Manual.

Environment

Not necessary.