Add 3D plotting support

One feature which I'd like to see is the ability to plot values in 3D. For some types of plots like scatter plots these may be defined as X, Y and Z arrays, but in other cases (like contours), specifying the bounds and a callback function to calculate values for arbitrary density may be preferred.

As for interactivity, it would be ideal if these plots could be rotated 360° in all directions (modifying only pitch and yaw, keeping roll at 0).

No files, tests, or entry points are named in the issue. Start by locating the plotting and interaction APIs for existing plots, then scope X/Y/Z data, callback-based contours, and pitch/yaw-only rotation; done means the requested 3D plot types render and can be rotated as described.

Written by the indexing model from the issue text.