[Visualpython-users] New stereo mode

I just modify a bit the vpython code to admit a new stereo mode called
"real".

This mode, try to simulate the real vision, what an observer view in the
real world. I have used the stereodepth as a half distance between
eyes, although I should have create a new parameter. I've used a real
vector rather normalized vector because,I think is more realistic. This
mode doesn't use the range (gcf) value, that it's not needed. You can make
the zoom using the user scale. This mode fix the point of view of the two
cameras separated by a given distance and look at the center.

It's the first version, and probably there will be things to improve.I need
this mode for my project, I'm working in a stereoscopic robot, and I using
vpython as a  way to represent (for now) a simple reality.

I attach the new code display_kernel.cpp display_kernel.hpp and ui.py

Best regards,