Here's my early draft of C rewrite/port

[alexisnaveros]

Hey people, here's an early version of my C rewrite/port of Clipper2. The API looks like this:
http://www.rayforce.net/clipper2c/clipper2c.h

And the rest of the code can be found here:
http://www.rayforce.net/clipper2c/

Results are identical to Clipper2's on July 9th... (okay, it seems some bugs have been fixed since that date, I need to check them out).

Based on one random test, this preliminary C version appears to be 6% faster than the C++ version?... I have reversed a couple experimental optimizations to maintain the code's structure closer to Clipper2, for now. I'll wait a bit for bug fixes and/or the outcome of scalability experiments (it's going to be messy if the code is completely transformed).

(ideally compile with -O3 -flto -march=native -mtune=native, or at least -msse4.1 -msse4.2, some optimizations are based on SSE 4.1/4.2 intrinsics)