D-Bot E3D V6 mount with BLTouch

This is a replacement for the D-Bot hot-end mount, with a similar design to my e3d Chimera/Cyclops mount. This one mounts an e3d v6 or clone, and a BLTouch sensor.

There's another mount, which replaces just the outer clip, on here, but I was having pretty substantial reliability issues with the BLTouch using it, because it wasn't sufficiently supported to not flex, likely because the mount was part of the outer clip and not rigidly mounted to the carriage.

This one replaces the rear mounting plate with a larger, and more rigidly supported mount for the BLTouch. Even with very fast probing on my Duet WiFi, I get about .005mm consistency across a 30-touch test probe using this mount. I was occasionally seeing variances as high as .02-.03mm with the other one, which was okay if it was being used as a Z-stop and multiple readings were taken, but wasn't usable for mesh compensation.