FR: Support for Circle Pad Pro accessory

[jackgraddon]

It would be very nice to support the Circle Pad Pro accessory for the o3DS(XL) so the o3DS can support all of the standard controller buttons an Xbox controller supports, just for those of us who have what we have and don't want to shell out a few hundred for a n3DS (even if they are vastly superior).

This, in addition to #17, would be very nice!