Reinforced Belt Tensioner: Nutless

The original source was too frail and kept breaking, and the remix by TERRAOperative added a square nut to the build; this build aims to retain the original nutless design while still being reinforced. When using it with the Anet A8 or similar printers, attach to the bottom end of the belt close to the extruder so as to avoid it jamming in either end of the belt.