SNES video output on the bottom screen

[beta215]

Giving the ability to display the SNES output on the bottom screen would be pretty interesting and useful: for 2|3DS devices with a broken top screen, for GB Macro builds, and for using the touchscreen as a mouse in Mario Paint (if the SNES Mouse gets implemented in that way).

There's also some people that doesn't like how the pixels on the top screen of 2|3DS devices look and the scanline it adds (except for the o2DS), so that's another use case for this feature.