Custom internal resolution as in PCSX2

[Starscream]

The only real internal resolution issue I see with Dolphin is that 1xIR is too "strong" of a setting for some Intel chips. If we had back the 0.75x or the even lower 0.5x settings that existed with Dolphin 3.0, these Intel graphic chips wouldn't be bottlenecking these strong Intel processors that come with weak IGP's and people would be able to play games at better speeds with crappy GPU's.