Add 3rd dimension

[verhovsky]

It would be cool if the processor could be rotated to reveal the stack of layers.

The source code for visual ARM1 mentions that it used to do this https://github.com/verhovsky/visual-arm1-highres/blob/ff33b4d1fc79837d2ae6bd5cfeea2d056796fb0f/sim/varm/geom.js#L21

[verhovsky]

https://gds-viewer.tinytapeout.com/

https://github.com/TinyTapeout/tinytapeout_gds_viewer

[floooh]

One thing that will be much trickier in 3D mode will be mouse picking, it would probably be a visualization mode only without picking, at least initially.