Custom Aspect Ratios are not available on Saturn Core

[wwark]

Hi,

At this line, https://github.com/MiSTer-devel/Saturn_MiSTer/blob/5d193adddf6a1914b9ab1a03263f7d53fcc22fb7/Saturn.sv#L258C3-L258C33 we have
"P1OA,Aspect Ratio,4:3,16:9;",

Other cores, we have this kind of configuration in core_name.sv file and it permits to set custom aspect ratio we want.
Aspect ratio,Original,Full Screen,[ARC1],[ARC2];

Thanks for your time of this great core 👍