Gregs-Wade-Kuheling Extruder support for i3 with fan support

This is a remake of http://www.thingiverse.com/thing:57668 - the format is SCAD rather than OOML (I've rewritten the SCAD model rather than try to "port" the original OOML code).

I've also added two extra components. The hinge allows mounting a fan frame (included). The two flanges are for this very basic bed leveling probe: http://www.thingiverse.com/thing:364017 (use the flange closest to the fan for probing, the other one for putting the probe away during prints).

This should be printed