Allow overlays installation for ratios other than 16:9

[cosmo0]

Some people use the tool to add overlays for vertical games on 4/3 monitors.

Allow other ratios, and resize/crop the overlays accordingly during installation.

[leandromacrini]

up vote

[ggtylerr]

Bump. I'm reusing an old laptop that has a 768p screen, which is close to 16:9 but not exactly, so the program does not recognize it.