Hall effect filament sensor for Clockwork 2

[ScramblerUSA]

My honest attempt to modify Clockwork 2 so that it includes a filament sensor, while trying to preserve stealth-geometry-style of the thing.

[MiguelFAlvarez]

No wayyy I just spent all of last night modifying the CW2 to add the hall effect sensor and then just noticed your pull request. Funny enough, I ended up with the disc and the magnet in the same position lol, but I added my sensor slot in the back instead. It still ends up in the same spot more or less. For mine, the sensor needs to be inserted before the magnet. I also had no issues with a normal 8mm screw used throughout the build, but the wall between screw and sensor is 1.2mm so that might be why.