The resource file format Hugo uses has named entries.
Because of this, the original Glk code added to Hugo
does a whole mess of reading in a picture, then copying
it to a dummy pic file with a dummy number, just so a
call to glk_image_draw could detect it.
Since this isn't the first time I've had to deal with
named resources, it ended up being cleaner to add a new
variation of glk_image_draw and glk_image_draw_scaled
that can take in a string image parameter. That way, I
was able to set up an archive class to represent the
resource file, and pass the resource name directly
without worrying about dummy picture numbers & files
