LABELSIZE

	(wxWidgets only) outputs a list of two positive integers, the width
	and height of characters displayed by LABEL measured in turtle steps
	(which will be different from screen pixels if SETSCRUNCH has been
	used).  There is no SETLABELSIZE because the width and height of a
	font are not separately controllable, so the inverse of this operation
	is SETLABELHEIGHT, which takes just one number for the desired height.