Color variations updates should be 100% automated, including thumbnails

[SebastJava]

You still have this old files/usr/share/themes for handmade color re-edits. Well, things recently got better, you no longer need to re-edit the gtk-2.0/menubar-toolbar since its now made all grey anyway. And the xfwm4 close buttons are finally automated. Great. But you still have to do:

• cinnamon/thumbnail.png
• gtk-3.0/thumbnail.png

One-by-one, handmade, for every color, in light and dark versions: 2 x 2 x 11 = 44 handmade edits. If these were automated, like everything else, it would open new doors:

• Quickly and easily update colors. Because you can change your mind at any time and because color trends are always evolving.
• Open the doors to some small application that would empower people to create their own color variations.
• Make things much easier for all those people making forks or clones from mint-themes.