FORM num width precision

	outputs a word containing a printable representation of "num",
	possibly preceded by spaces (and therefore not a number for
	purposes of performing arithmetic operations), with at least
	"width" characters, including exactly "precision" digits after
	the decimal point.  (If "precision" is 0 then there will be no
	decimal point in the output.)

	As a debugging feature, (FORM num -1 format) will print the
	floating point "num" according to the C printf "format", to allow

		to hex :num
		op form :num -1 "|%08X %08X|
		end

	to allow finding out the exact result of floating point operations.
	The precise format needed may be machine-dependent.