3Dator Bowden Extruder REMIXED (MK8 GEAR) base mod 1/8"

Another simple remix of the [3Dator Bowden Extruder REMIXED (MK8 GEAR)](http://www.thingiverse.com/thing:1679553) that provides a 1/8" inside thread to take the PC4-01 push fitting for the PTFE tube. I've included the OpenSCAD file that I used to create the mod. With the PC4-M5 push fitting used in [this design](http://www.thingiverse.com/thing:1757032) I noticed unwanted movement of the PTFE tube on retraction as [witnessed](http://www.thingiverse.com/thing:1757032/#comments) by [50koruny](http