[Visualpython-users] update

Minor update to downloads on the VPython web site. New versions of the demo 
programs stonehenge.py and toroid_drag.py to use the new mouse machinery 
and implement dragging with mouse button down.

To my surprise, stonehenge worked fine after merely inserting scene.newzoom 
= 1. On the other hand, toroid_drag needed some modest restructuring.

Bruce Sherwood