Sector procedure

  DECLARATION:  Sector(X, Y : Integer; StAngle, EndAngle,
                       XRadius, YRadius : Word)

      PURPOSE:  Draws and fills an elliptical sector

         UNIT:  Graph

      REMARKS:  Sector uses (X,Y) as the center point, XRadius and YRadius
                as the horizontal and verticle radii (respectively), and
                draws from StAngle to EndAngle.  A StAngle of 0 and an
                EndAngle of 360 will draw and fill a complete ellipse.

                The sector is outlined using the current color, and filled
                with the pattern and color defined by SetFillStyle or
                SetFillPattern.

 RESTRICTIONS:  Must first be in graphics mode.