Allow for RPI / Single Board Computers - a scaling system to scale a 320x240 resolution to fullscreen

[atsb]

I think this will make a lot of sense for those playing on a Single Board Computer. Right now it is either to play in a window, use a really small fullscreen resolution or to use a 7" raspberry pi screen.

A more ideal situation would be to allow the window to scale a 320x240 resolution so that it will upscale to fill the full monitor. We would also need to disable the resolution selection for these SBC computers. Then it would provide a very playable default configuration.