Accessing the name of the input file from inside LilyPond

[Mike Solomon]

Hey all,

I'm trying to find a way to access the name of input file (i.e. foo.ly) from 
inside LilyPond.  I know that this information is stashed in the parser (and 
thus accessible from music functions), but I would like to use it in a markup.  
Is there a way to get it from w/in markups?  The reason I'm doing this is kinda 
technical, but suffice it to say that I can't hardcode the file name into the 
markup in advance.

Cheers,
Mike