German RepRap Neo E3D v6 reduced

This is my remix of the excellent design by Kakadu, which should be easier to print and fit better.

Changes applied

* sliced design so that no support is needed and the LM8UU bearings fit well without much post-printing actions (that's all the files without 'mod')
* modified version of Axis mount, which hides the Din912 screws inside to have more space for the energy chain (which I've upgraded to a larger one, therefore the need)
* modified version of fan duct (to be verified it's better, I use the one by Kakadu still which seems too close for me to the bed)
* modified Axis bot and top, as the belt was imho not straight and rubbed on the hot end cooler
* keep the belt straight by having an angle in there
* enlarged slot for the other side of the belt

There's still room for improvement, e.g. the thin pieces could resized to look less ugly, but I'm happy with the state presented :)

Thanks to Kakadu again for his design, it's great and almost a drop-in replacement to th