Original Prusa i3 MK2 Adjustable Y Belt Holder

This was remixed from i3 Adjustable Y Belt Holder for GT2 & T2.5. The base was made thicker and the belt holder was shifted farther away from the end so that the holder can hit the Y endstop without running into the motor. The belt holder assembly was also made shorter front-to-back to fit within the standard Prusa i3 MK2 configurations, so it doesn't hit the motor at one end and the belt holder at the other. When mounting, the adjustment screw should point towards the front of the printer.