TODO:
- Implement iterative Douglas-Peucker, Visvalingam-Whyatt and Zhao-Saalfeld.
- https://github.com/mapnik/mapnik/blob/094994ef540353b846490bf5c0dd127d00740dcb/src/simplify.cpp
- https://www.cs.swarthmore.edu/~adanner/cs97/s08/pdf/speedingPeuckerDouglas.pdf
- https://hydra.hull.ac.uk/resources/hull:8338
- https://bost.ocks.org/mike/simplify/
- http://web.cs.sunyit.edu/~poissad/projects/Curve/pdf/1999.pdf
- https://www.researchgate.net/profile/Christopher_Jones10/publication/220649875_Characterisation_and_generalisation_of_cartographic_lines_using_Delaunay_triangulation/links/0046351fa40de62a28000000.pdf
- Maintain topology http://www.geoinfo.info/proceedings_geoinfo2006.split/paper1.pdf