Bowden tube wire clip

Used for holding wires against a Bowden tube. These clips are easier to remove/replace than kapton tape! Printing considerations:

* 100% infill

* print more than one at once to avoid the need for cooling (move to opposite corners of your bed)

* choose your extrusion width so that `clip_width` is a multiple of it

Edit: For some reason this doesn't work in Customizer; if anyone knows why, let me know, and I will re-add the 'customizer 'tag. For now I have disabled it. Just downlo