(Yet Another) 1.75mm Filament Spool Clip

This is a slight improvement on the filament spool clip from Thing #270739. I found that with the original, it was too easy for the filament to slip back out through the hole, and the filament clip did not clamp tightly on the spool, depending on the characteristics of the spool. This version improves the clip in two ways: (1) Adds a tab next to the hole that puts pressure against the filament and keeps it from slipping back through the hole, and (2) decreases the space in the clip's rest position so that it will clamp more tightly to the spool.

I was not aware of http://www.thingiverse.com/thing:229593 when I did this, or I would probably have used that as a starting point. May incorporate that OpenSCAD code into this project and add the tab to it; some day. . .