Add yet another wave of 3D wallpapers

[MultisampledNight]

This adds another wave of 3D wallpapers, which are more of a modern take than a simple one.

A few questions:

• I also created a .blend file of the logo, should I submit that one, too?
• One .blend source file is really big (gear.blend with ~90 MiB), which even caused a warning suggesting to use Git LFS. Should I just delete the sources? Switch to Git LFS? Use another file format?
• For the sources, I created a subfolder source in wallpapers to avoid cluttering the wallpaper directory itself. Is that okay?

[MultisampledNight]

Sorry if this comes over as rude, but is it possible that new wallpapers are unwanted in general? #66, #41, #60 and #68 have all been laying bare for quite a while. If that's the case, it'd be nice to add a note to the README listing that new wallpapers are not wanted.

[jonringer]

I think the main thing is that not a lot of people are subscribed to this repo.

Personally, I think they look really cool!

cc @samueldr

[dasJ]

Are there even people who can merge here apart from the RMs?

[dasJ]

I guess not