"extent" documentation is incomplete and unclear

[jdmarch]

Feedback from a user:

The problem is that the extent parameter is used in points3d, axes, and outline, but it does different things. When used in points3d it just rescales the coordinates so when axes is called (w/o the extent parameter) it adds axes to these rescaled coordinates. On the other hand, if you use points3d w/o extent and then call axes with extent if will draw axes according to extent. So for example if the extent of my data is [-10,10,-10,10,-10,10] and I just call points3d w/o extent and then then call axes with extent=[-100,100,-100,100,-100,100] then I will have the axes around a cube with 200 sides, and my points will be a tiny blob in the center.