Parametric Filament Clip

This is a slight rework of the same named item by qubit01.

The differences are:
* I made the wall thickness of the filament holder portion automatically calculated
* Re-formatted the file to match my style preference.
* While I was at it, I fixed the subtracted shapes by making them bigger by 1mm, and moving down by 0.5mm so they stuck out by 0.5mm on both sides. Because there was zero overlap between the primary and subtracted shapes, this causes a “skin” of thickness 0 which is