* usr/share/pixmaps/xubuntu-logo-menu.{png,svg}: new version, should
  be visible on white themes too (also temporary, new artwork on its way).
  lp: #526660
* Add new package, xubuntu-plymouth-theme, recommended by xubuntu-artwork.
* lib/, debian/xubuntu-plymouth-theme.*: added, new *temporary* plymouth
  theme, until the new artwork is ready (the letter 'x' isn't ready in
  the new font ;).
* Drop usplash theme.
* usr/share/themes/MurrinaXubuntu: dropped, not maintained by the artwork
  team, was just a test.
* debian/copyright: updated.
* debian/control: xubuntu-gdm-theme: demotes xsplash to suggests, doesn't
  interact well with xfce4-settings-helper, and doesn't seem actively
  maintained anyway. lp: #531410
* usr/share/xfce4/backdrops: dropped some old wallpapers again.