Modded MK3S Extruder

This is based on the new R4 or MK3S extruder set and modded to be used with [1A125VAC microswitch](https://www.thingiverse.com/thing:3438084) as the filament sensor. It would take months to have the prusa's filament sensor hit the conventional market.

I designed this because I am sure that the prusa's optical endstop won't be available that easily and I wanted to use with hardware that can be sourced easily.

Main difference between original extruder for MK3S or R4 and this MODDED is:
- Us