Anycubic i3 Mega Silent Hotend Housing & Fan Duct

This modification eliminates these issues:
- reduction of fan noise
- eliminates the air flow from cooling fan of the hot-end towards the heatbed

Notes:
* The front panel is fixed using filament pieces that need to be inserted into the holes (can be fixed with cyanoacrylate glue).
* The parts are printed from ABS.