prototype: multi-match templatematching

This prototype module demonstrates a method for getting multiple matches
of a template against a source frame. The essential idea is to consider
points from the heatmap (i.e. cv2.matchTemplate(...)) which fall within a
certain percentage boundary of the strongest point. I've dubbed this value
the `cutoff` point, and it requires a high value to prevent too many
possible match point being found. The script will exit if too many match
points are found because they must all be clustered together by comparing
each pixel to each already-clustered pixel, which obviously grows very
rapidly.

For some of the example source/template pairs I've given, the minimum
value needed to avoid either a false match or excessive match points are:

one-page / unselected-vod-player : 0.9989
many-pages / unselected-vod-player : false matches before true matches
   (the template does not work for this frame)
one-pages / o : 0.91 (lots of true nomatches)
many-pages / o : 0.983 (matches 'o' in 'Comedy' crumbtrail otherwise)
xsnos-source / xsnos-template : 0.875 (misses true matches at 0.87)