Moving the kernel to modern C

It's also more difficult to read for me, but way less than if I cannot trust any of the most elementary operators anymore.

A good example are the mmx/sse/avx* API with all those complicated functions that map 1-to-1 to the underlying instructions. It's particularly hard to read, but it would be even worse if operators were abused to perform some of them. And there are still much less operators than possible functions anyway, so being a bit more explicit doesn't hurt.