Wanhao i3 mini FanDuct with FanCover

Rework of the impressing desing of MAL_0703 to replace the stock fan mounting and improve part cooling

- made it shorter (and a bit simpler), no need for shortening anymore
- changed holes for mounting screws to long holes for individual adjustment as there seem to be different versions of hotend mounts around
- added a cover for the fan
- duct printed with 0.2/25%
- cover printed with 0.15/25%
- everything mounted using stock parts

Cooling effect is significant. After printing and mo