Removes the TTL triangulator in favor of the delaunator triangulator.
This removes the only AGPL code in the KiCad codebase and therefore
allows the full project to be licensed under the GPLv3.
* Split up the thirdparty code into the thirdparty folder (#3637)
* Create a new kimath static library containing all the math functions
This is part of cleaning the build system for #1906.
Seth Hillbrand
Thomas Pointhuber
Ian McInerney
Jon Evans