Hobbed Gear and Idler Bearing for Prusa MK2.5

Small additions/changes to Joshua Payne's hobbed/bearing modification. X-Carriage is compatible with MK2.5 and the idler uses bearing like this:

https://www.amazon.com/gp/product/B075CLMYRT/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I cut down a longer M3 bolt for the idler pin.

Use klystron's extruder body with these parts.