A8 Fan Shroud for Quick Filament Changes

Changing filament on the A8 is tricky b/c you can't see the filament feed path. 75% of the time, I couldn't get it to work, and found it was "easier" to unscrew the whole extruder mechanism, which is preloaded by the spring and etc. -- a pain in the rump.

There are a few good solutions out there. Mine's a minimalistic combination of two of them.

In particular, I took the cut-down-the-heatsink approach and inspiration for the half-shroud from [nicolaidiz] https://www.thingiverse.com/thi