[Feature Request] Support font family subfolder

[knowhan]

Right now Liberera doesn't recognize subfolder under designated font location, so you have to put all font files in same directory, and set regular, bold, italic, etc font separately.

I find Reasily done this better, if you add a '@' character to the end of the subfolder name, it'll group them as a font family.

Could you consider add this feather?

Thanks.