spiro.icn: Program to display spirograph lines

Comments: This program displays spirograph-like output
    There are two methods of drawing: epitrochoid, where
    the secondary circle moves around the outside of the
    primary circle, and hypotrochoid (the default here),
    where the secondary circle moves around the inside of
    the primary circle.

    See the procedure 'helpmsg' for command line options
     (or run as 'spiro -help')

    Waits for a window event before closing window