Add Gamecube controller, using wisegroup USB converter

Was sorting out some things to eBay and discovered this little box I
forgot I had. Allows a single controller to plug into USB. Sadly does
not support the Wavebird. Also lacks a reasonable amount of buttons, so
use at own risk of sub‐par experience.
Merge pull request #4 from johndrinkwater/master

Add Gamecube controller, using wisegroup USB converter