Improve output system

[ferrouswheel]

Make each output class subclass a super.

output PNG to directory output/png and generally produce sub directories for each output type

split analysis command into output/<command-name or alias>

provide a movie output command

[ferrouswheel (joel-pitt)]

Make video using pymedia?

http://pymedia.org/tut/src/make_video.py.html

or use imagemagick to create animated gif from images.