Edge detection node for cycles

Pointiness is great feature, but it does not work with low poly meshes very well. So we need a node, that could find the corners from the model and draw them. There already is one OSL shader, that creates good job with this, but you can't render OSL shaders with GPU, so I think we really need this to Cycles core.

Here is the thread of that OSL shader:

blenderartists.org/forum/showthread.php ;