Return information about a font named NAME on frame FRAME.
If FRAME is omitted or nil, use the selected frame.
The returned value is a vector of OPENED-NAME, FULL-NAME, SIZE,
HEIGHT, BASELINE-OFFSET, RELATIVE-COMPOSE, and DEFAULT-ASCENT,
OPENED-NAME is the name used for opening the font,
FULL-NAME is the full name of the font,
SIZE is the pixelsize of the font,
HEIGHT is the pixel-height of the font (i.e., ascent + descent),
BASELINE-OFFSET is the upward offset pixels from ASCII baseline,
RELATIVE-COMPOSE and DEFAULT-ASCENT are the numbers controlling
how to compose characters.
If the named font is not yet loaded, return nil. (fn NAME &optional FRAME)