[8pt] UI: A basic 3D plot example for Implot (mountain range or 3D surface plot)

[ivan-cukic]

There are basically three plot types (the first two are strictly-speaking still 2D, here: RF/accelerator-related examples):
A) ~70% use-case: contour/heat-map/2D Histogram -- there's a myriad of ImPlot examples, e.g. here or here

B) ~10% use-case: mountain range (similar to the above, older/sometimes preferred: data reduction & better vertical scale)

C) ~20% use-case: 3D surface and cloud density plots (qualitative examples only)

The primary open questions to be answered are:

• Performance: CPU load when plotting a simple 2D sine wave and 2000x2000 points @ 25 Hz
• Integration of the true 3D plot with the other ImPlot plots (i.e. API-compatibility/similarity)

[ivan-cukic]

Focus on A) and B)