We do not need to update gtk-bookmarks on laptops anymore
(except remove some old stale ones)... some other mostly
stylistic changes.
Run puavo-update-gtk-bookmarks from "Xsession.d"-scripts
instead of xdg/autostart.  The problem is that some desktop
desktop component, maybe Nautilus, may read the bookmarks
and write them back soon after, and thus the
puavo-update-gtk-bookmarks script may have no effect at all.
Changing the run order in this way appears to solve the problem.