SetAspectRatio procedure

  DECLARATION:  SetAspectRatio(var Xasp, Yasp : Word)

      PURPOSE:  Changes the default aspect ratio

         UNIT:  Graph

      REMARKS:  Each graphics mode and driver has an associated aspect ratio
                (maximum y resolution divided by maximum x resolution).
                SetAspectRatio is used to change the default aspect ratio of
                the current graphics mode.  The aspect ratio is used to make
                arcs, circles, and pie slices round.

 RESTRICTIONS:  Must be in graphics mode.