LineRel procedure

  DECLARATION:  LineRel(Dx,Dy : Integer);

      PURPOSE:  Draws a line to a point from the current pointer (CP)

         UNIT:  Graph

      REMARKS:  This will draw a line from the current pointer to a point
                that is a relative distance (Dx,Dy) from the current pointer.
                It will use the current line style, thickness, and color.

                The current pointer is set to the last point drawn by LineRel.

 RESTRICTIONS:  Must first be in graphics mode.