Small doc error & clarification

[JimC]

Actually, I think it's just me not realizing that viz.phys.intersectLine() and viz.intersect() behave differently when all==True. viz.intersectLine() tells you which objects are intersected (one intersection/object), whereas viz.intersect() gives you every intersection point (e.g, where the line intersects front _and_ back faces of the same object)--which is the behavior I was looking for.

I guess the docs could be a bit more explicit about that.