Kept the old hacks where they don't break the build in case they things
they fix are still relevant.
I checked that the upgrade doesn't break:
1) Asymptote and EProver builds.
2) My XeLaTeX demo from configurations/ repository.
3) Some of my own files.
The upgrade fixes problems with simultaneous use of 3D and LaTeX labels
in Asymptote.
Please provide a test that worked previously and is broken now if you
need to revert this update or its parts.
See #490 discussion.
This reverts commit 1278859d31, reversing
changes made to 0c020c98f9.
Conflicts:
pkgs/desktops/xfce/core/xfce4-session.nix (take master)
pkgs/lib/misc.nix (auto)
Vladimír Čunát