Added contour visualization method.
Added Object methods to Pupil_Regions.
Changed to best fit pupil and avoided eyelashes.

The detect method in Simple_Detector now does two additional things:
  - Oblong contours, like those generated by eyelashes, are now
    removed from the image and a new set of contours are generated
    without them.
  - Rather than choosing the first contour that could be a pupil,
    we go through all the contours looking for what could be the
    best one based on how full it is and how square it is.