Allow custom fonts

# Feature Request

I would like the ability to have the ability to have the font I use for all my development [FireCode](https://github.com/tonsky/FiraCode) to be included so its pushed to the client.

I'm not really a star when it comes to CSS, but maybe this would be possible with something like a `@font-face` which would push the font to the client. Then when you configure the font in Code, because its pushed to the client you can have the FireCode font and ligatures without installing the font on the client.

I would also accept solutions from anyone, how to hack some files to get this working.

Hopefully I'm not the only one using this font.

With Kind Regards,
Gert-Jan Timmer