Include some of the generally useful gpl palettes by freiefarbe.de

Christoph Schäfer suggested to include some of the gpl (file format, not licence) color palettes created by the freiefarbe.de project.

He picked some palettes that he thinks will be of use to a wider audience.

The palettes' licence is CC-By-SA-ND.

The selected palettes are attached, for a preview. If devs agree this would be useful and the licence isn't an issue for this, I'll make a merge request, also with an adapted licence file (removing files that are not included from the list).