Add `syslinux.gpl' and `grub.gpl' files to default design models
directory structure.
- These files are used when no background information is available
for design models.
- These files are used as template to create both syslinux and
grub palettes inside themes' artistic motifs, when no palette is
found there.
- The color information used here is for default design models
without background information. If you are producing syslinux
and grub artworks with background information, you need to
update the value of the color information inside both
syslinux.gpl and grub.gpl files in order to match the color
information of the background image you are using on.