RepRapGuru X Endstop Mount

Proper X endstop mount for RepRapGuru's Prusa i3 V2 kit 3d printer.

The original endstop mounts for the Makerbot endstops are very difficult to get aligned and the endstops don't sit flush against the mount. This mount clips on to the X rails (very securely) and only needs one M3 screw and bolt to hold the endstop down. The mount can be made wider with the "extra_distance" parameter in Fusion 360 to keep it in position (but the narrow version doesn't slide easily). On my printer (with changed