Alternate Belt Tensioners for Re-D-Bot

I got tired of messing with the fiddly little bits on the belt holders/tensioners on my Re-D-Bot carriage, so I altered them a bit so they don't require so much hand holding when detaching/attaching/tensioning belts.

These belt tensioners will hold onto the small half cylinder bit that actually tensions the belt. The original version doesn't, and that half cylinder would move around and get twisted and chewed up by the screw. My version has rails that guide it, and a much deeper socket for t