They are not being used any more. For some reason people thought that an exception was made for extruders or something. And people keep adding them for the definition files too. I'll add a test to prevent that.
This should fix some underextrusion problems... Hmm.
Sources:
* https://alya3dp.com/pages/teknik-ozellikler
* https://www.creality3d.cn/creality-cr-10-s4-3d-printer-p00098p1.html
* https://www.creality3d.cn/creality-cr-10-s5-3d-printer-p00099p1.html
* https://3dprint.com/3643/german-repraps-neo-3d-printer-now-available-in-the-us-uk/
* https://somosmaker.com/pegasus-impresora-3d/
* http://www.3dmaker.vn/3d-printer-3dmaker-starter/?lang=en# (assuming the filaments they sell on that website are compatible)
* https://makezine.com/product-review/printrbot-play/
I could not find a source for the Deltabot, but got that information from here: https://github.com/Ultimaker/Cura/issues/4573
Contributes to issue CURA-5817.
