I’d like to write some current settings to a file, using `io.savedata`.
How can I get information about the current font, or even better, the current settings for `\rm`, `\ss` and `\tt`?

EDIT: fontconfig must be able to cope with the font name. I want to pass the font from ConTeXt to GNU LilyPond.
See <http://wiki.contextgarden.net/LilyPond>