Mendel90 fan duct for e3d hotend

Keeping the original Mendel90 fan duct shape, this one is adjusted so that it fits the e3d v5 or v6 hot end.

The height of the duct on the nozzle is reduced so that it fits nicely, and the height on the fan side is increase to cope with the longer head.

The origin fan duct was 20mm height. Two versions are included in this thing with both 15mm on the nozzle side. On the fan side, one is 31mm thick, the other one is 25mm. Check the space you have left, and adjust with washers if needed.