Created by: portnov
Given a mesh, calculate normals for its faces and vertices. Partly functionality of this node intersects with "Centers polygons" node, but: 1) "Centers polygons" cannot calculate normals of vertices, 2) "Centers polygons" cannot calculate normals for meshes without faces, i.e. for curves. On the other hand, "calculate normals" has nothing to do with matrices, as "centers polygons" does. See also portnov#20. Please review.