Replicator 2X E3D-v6 upgrade - adjustable

Based on the awesome work by cadsys, but with a few tweaks and improvements.

The extruder mount is slightly modified to take a wider range of extruders, including the cheap chinese aluminium ones I had on hand. The hot end mount is now one piece as I found it hard to get the clip on fan mounts to sit in the right spot without them sliding around. The hot ends are also easily height adjustable with a single locking screw to slide them up and down. The catch is that the hotend mount now requires support to print, but the original fan mounts did anyway so its not that much of a compromise.

Drill out the holes in the hot end sliders to 2.5mm before tapping them M3. Because they go through the print sideways be *super* careful with your tap and go slow or the part may split. Try increasing your print temperature by 10 deg when printing the sliders, the extra layer adhesion should make them a bit stronger.