Added configurations for the following RatRig printers:
* RatRig V-Core 3 (200mm, 300mm, 400mm and 500mm versions)
* RatRig V-Minion
V-Core 3.1 modification is also supported.
Bed meshes are taken from https://github.com/slic3r/slic3r-profiles with kind permission of the author @HelgeKeck