Return information about FONT-OBJECT.
The value is a vector:
[ NAME FILENAME PIXEL-SIZE SIZE ASCENT DESCENT SPACE-WIDTH AVERAGE-WIDTH
NAME is the font name, a string (or nil if the font backend doesn't
provide a name).
FILENAME is the font file name, a string (or nil if the font backend
doesn't provide a file name).
PIXEL-SIZE is a pixel size by which the font is opened.
SIZE is a maximum advance width of the font in pixels.
ASCENT, DESCENT, SPACE-WIDTH, AVERAGE-WIDTH are metrics of the font in
CAPABILITY is a list whose first element is a symbol representing the
font format (x, opentype, truetype, type1, pcf, or bdf) and the
remaining elements describe the details of the font capability.
If the font is OpenType font, the form of the list is
(opentype GSUB GPOS)
where GSUB shows which "GSUB" features the font supports, and GPOS
shows which "GPOS" features the font supports. Both GSUB and GPOS are
lists of the format:
((SCRIPT (LANGSYS FEATURE ...) ...) ...)
If the font is not OpenType font, currently the length of the form is
SCRIPT is a symbol representing OpenType script tag.
LANGSYS is a symbol representing OpenType langsys tag, or nil
representing the default langsys. FEATURE is a symbol representing OpenType feature tag. If the font is not OpenType font, CAPABILITY is nil. (fn FONT-OBJECT)