Prusa i3 Rework Extruder Upgrade

I've recreated the extruder body from the Prusa i3 rework, then translated the motor mount about 5mm toward the -x direction in order to make it easier to then switch the gears to the herringbone design, based on changes to the script by ScribbleJ (also the hex insert is now sized more appropriately for an M8 hobbed bolt than the original). The tooth ratio on the gears is 37/13 (original was 43/10, so adjust esteps accordingly).

Also, I increased the size of the holes slightly on the idler and added a thumb grip to make it easier to use. The fan duct and X carriage are unchanged but included here for completeness.

This is also the extruder now maintained as part of the reprap Wilson design.

UPDATE 5-21-14: I have made some small tweaks to the body and idler to make them easier to print, decreased the fulcrum width a smidge on the body, increased the filament guide hole by .15mm, and made the slots in the idler a little narrower.