Someday: use a 32-bit depth buffer

[sjackso]

Athena up to v0.3.5 shows bad z-fighting artifacts in its ray-traced output objects (cylinders, spheres, cones). v0.3.6 and later address this by choosing a better front plane for perspective projection.

What I really want to do, to address this more completely, is to change Athena's depth buffer to 32 bits instead of 24. Unfortunately this does not seem to be possible with today's PySide2 and Qt3D, because:

• Qt3DWindow.cpp unconditionally sets a 24 bit depth buffer, and
• It doesn't seem possible to set up a new OpenGL context in a child class, and
• It doesn't seem possible to control the actual buffer depth by first enabling shared OpenGL contexts (I tried), and
• Reimplementing Qt3DWindow in Python code is impossible because of a PySide2 bug. (Maybe it'd be possible under PyQt5?)

Once a 32-bit buffer can be enabled, it would be worthwhile to reverse the Z buffer per this article to gain a complete upper hand over these kind of rendering artifacts.