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