This replaces the functionality of the polyvox library, so we don't have to ship it anymore. :)

This will to introduce a bit of a breaking change, where if borders are filled in, then the faces at the border is not rendered. But considering, that polyvox already did it at some of the sides, I tought it would be better to always not render faces there, so that tiling can be done in the future. This can be changed back if needed