Conforming/Constrained Delaunay

Conforming or constrained triangulation would be utter-cool. Input can be points, lines and polygons while output edges will not cross existing input edges. _Conforming_ would introduce new points in order to be true delaunay triangles (steiner points) while _constrained_ is not always truely delaunay but doesn't introduce extra points.

Relevant information:
- [http://www.cs.cmu.edu/~quake/triangle.defs.html#conform](http://www.cs.cmu.edu/~quake/triangle.defs.html#conform)
- [http://www.cs.cmu.edu/~quake/triangle.delaunay.html](http://www.cs.cmu.edu/~quake/triangle.delaunay.html)
- [http://lin-ear-th-inking.blogspot.nl/2009/04/delaunay-triangulation-in-jts-111.html](http://lin-ear-th-inking.blogspot.nl/2009/04/delaunay-triangulation-in-jts-111.html)

Start with the external Triangle and JTS references linked in the issue, then inspect the repository's current triangulation API and implementation. Done means supporting points, lines, and polygons without crossing input edges, with conforming mode adding Steiner points for true Delaunay triangles and constrained mode avoiding extra points.

Written by the indexing model from the issue text.