plot3d: tube_radius active for representation='points'

I just spent three days tracking the most ridiculous issue, which turned out to be a documentation problem.

Basically, plot3d(x,y,z,representation='points') does **not** plot the points at locations x,y,z but rather at a distance 'tube_radius' from x,y,z , which is not a behavior anyone would naively anticipate from the semantics as no tube is being drawn. For a complex dataset, these points appear to lie at random places a distance tube_radius from where they should be.

Nowhere in the docs we are told to use 'points3d' rather than 'plot3d' if the intended plot is a point scatterplot. What plot3d tries to do when told representation='points' is pretty strange and hard to imagine from the docs.