7.6.2pre3

All the recent changes enumerated below. Also updated some dependencies in the lab extension to eliminate some vulnerabilities.

Enable changing menu choices
clock() works with pre- and post-Python 3.8
Improve ring texture and bumpmap
Improve appearance of helix
Fix bugs with zero-length objects
Can gray out a slider using slider.disabled = True
Fixed an error in rounding an extrusion shape
Speed up creation of compounds
Implement object.bounding_box()
Fix bug in setting depth of 3D text
Fix bug in graph object data attribute
Fix error reporting in use of curve.pts(N)
Implement round arrows