Potential June Release of CadQuery 2.6

[jmwright]

I would like to do a June release of CadQuery, which will be 2.6. There are some PRs that we should probably try to merge before that release. Below is a list of the PRs that I'm aware of that are close enough to merging to make the June release window.

• Material support - A larger PR, but it would be nice to include this in the next release.
• STEP assembly import - I have this mostly working, I'm just checking a few issues before I take it out of draft.
• Update of copyWorkplane - Whether we want to merge this one or not, it seems reasonable to review it before the release.
• Non-blocking vis.py Support - This may need to wait for new releases of upstream packages, I'm not sure. We will try to merge this one.
• extend _findFromPoint to support Vertex

Thoughts?