Remix of Bowden Tube Straightener for UM2+

Remix of the great "BowdenTube Straightener" by TheSeend adapted for an Ultimaker 2+ and Ultimaker Extended 2+. What are different in this remix : - the bowden straightener region is now circular, in order to straighten the tube during printing in all surface of the building platform, especially the back area to avoid flexion of the bowden and reduce friction of the filament into the bowden. - the distance between the two screws axis, the diameter of screw heads and the space for the clip were measured and re-adjusted - the square hole has no particular function, but is just there to reduce the amount of material without decreasing mechanical strength Files are available in STL and STEP formats.