Working on KD-tree.

Trying to implement KD-tree for the ray tracer, I solve appearing problems with both environment and the language itself.
Anyway, the result can be found any moment on the github.

Currently I am working on KD-tree, on the build-tree function, to be specific. The most difficult part of it seems to be a SAH function (surface area heuristics).

And the next difficult part would be a traverse-kd-tree function, which is implemented, but I am looking for good testing techniques for it: a 3D geometrical data is difficult to visualize either in console or on screen.