Belt Anchor for Makergear M2 to M3 extruder conversion

This is a remix of tslove28's M2 to M3 conversion. I've only modified belt anchor slightly. After conversion extruder sits about 10-15 mm offset to the left side. This means if you were using custom GCode like one that moves extruder off the right side of the bed to get filament flowing before you start the print, it will now dump filament right on the bed unless you adjust the code. Problem for me was that I use same profile for multiple M2 printers and I didn't want to remember to use special one for modified one.
Solution was simple. I added a small protrusion on the left side so now it engages X axis endstop sooner when homing. This worked out great, now position of nozzle on my upgraded M2 is same same as on unmodified printers. I also enlarged tops of the holes so it's easier to thread the screws.