Add example for Meshing with TriangleElement

[epsi1on]

Add an example for mesh with TriangleElement.
A polygon surface with holes and constraints that uses Deluanay Triangulation for mesh.

[epsi1on]

Example is not created yet. :)
I just made an issue for it. It is like TO-DO list, I'll make the example as soon as possible.
By the way ,have you checked the other code i sent you earlier? did you find it helpful?

[epsi1on]

Sorry, Maybe my code is clumsy and complicated to be simply readable. That is not entirely "Clean Code" and I know it :)

It just need a little effort I think. Feel free to ask questions here.