Reasonably universal bowden swap kit

As I find more pieces I'll add them to the collection... marked "WIP" because of that. The current files won't change unless somebody has recommendations.

I have created adapters to change the standard 50mm-spaced extruders (all Prusa2 carriages and Wades-compatible extruders, including Greg's Accessible) into a Bowden setup. This will allow you to move the heavy extruder motor off the X carriage and mount it rigidly to your frame instead.

Currently sized to fit Arcol and Budaschnozzle h