ENH: Add icons

[marsipu]

This PR adds custom icons from Google's material design.

[larsoner]

@hoechenberger this is probably for you :)

[agramfort]

can you share a screenshot? 🙏

[hoechenberger]

Good job so far, already much better than before! I'd have some recommendations for further improvements if you're interested. But this is already a great step up, thank you!

[marsipu]

@hoechenberger thank you for the screenshot.
I asked Guillaume which icons he used for the pyvista-backend and added the icons from Google. Then I adapted some of them in Inkscape (less channels, less time).
I am open for improvements and suggestions, @hoechenberger what do you have in mind?

[marsipu]

@hoechenberger You said you had some suggestions for further improvements?

[hoechenberger]

@marsipu I will get back to you later today 👍

[hoechenberger]

… just give me until noon … 😅

[hoechenberger]

@marsipu Sorry for holding you off here, I'm just too busy with other stuff right now, my apologies. Please go ahead and merge if you're happy, and once I have more time again, we can iterate with additional tweaks. This PR is already a huge step up so I think it should be merged ASAP. We can make things even better at a later time!

[larsoner]

Agreed, maybe needs a rebase or merge with main to get tests passing here?

[hoechenberger]

@larsoner This branch is up to date with main, maybe try just restarting CI?
(I cannot do it for lack of permissions – I'm not an admin / maintainer of this project)

[larsoner]

Okay, now even more CIs failed :)

[hoechenberger]

🙈

[marsipu]

I think the fails are fixed in #54 which just got merged. Try rebasing again on main now