Also move the grub theme to /usr/share/grub/themes/kali/ as installing
files in /boot/ is problematic on arm where /boot is often a vfat
partition that doesn't support hardlinks as required by dpkg.
Gbp-Dch: Full
* Provide 3 common ratio (16x9, 16x10, 4x3) for the 2 main images.
* Avoid duplication by creating symlinks for all the screen sizes needed by
KDE. We link to the picture with the closest ratio.
* Make all background pictures available to gnome-background-properties.
* Make the 2 main background pictures available to KDE.