Smootiebox - slim - dumle-remix

I remixed the very nice case from mdietz, and added a 12mm hole near the endstop connectors, I moved the stepper hole to the side, to add slots for M5 bolts, to allow the case to be bolted to V-slot directly. I also added a cutout for a 40mm fan in the lid.

Additionally I modified the openscad file to be more user friendly with the customizer, and allow the user to specify custom fan sizings, if they want fans or not, and if they want the vslot mounting holes.