A8 PTFE Guide Tube Mount

The stock Anet A8 setup can jerk the spool around too much during travel moves, which can tangle up the filament, especially when you use a low friction spool handler (like this: https://www.thingiverse.com/thing:1241566). The solution is adding a 2mm PTFE guide tube secured to the frame on one end, and shoved into the top of the extruder on the other end (like a bowden setup with the motor on the wrong side). This thing secures the PTFE tube to the frame using a standard bowden tube slip fittin