WIP: Init mayavi at 4.6.1

[knedlsepp]

Motivation for this change

This adds the mayavi package. I originally based this on a commit in June 2018 (1d1a4bf), where the mayavi GUI worked. When I rebased it onto current master, something did break, which now leads to a segmentation fault.

Help is very much appreciated.

Edit:
The segfault seems to be due to some environment impurity (QT maybe?), since it runs fine when inside a nix-shell -I nixpkgs=$PWD -p python2Packages.mayavi --pure,
Could probably be fixed via: #54525

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

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[costrouc]

What is the status of this PR?

[knedlsepp]

Needs revisiting now that #54525 could solve the problem.

[FRidh]

While it may not work, it's in the right direction and I think it's an important package to support, although it is not as popular anymore as it used to be.

[knedlsepp]

Oh. Thx @FRidh. I forgot about that one already. I'll try to check if applying some wrapqtappshook will solve the issue.