Start part 3 with extended pipes section.
Update the syntax highlighting.
Add chrome_watcher.rb to watch for content changes and refresh.

VERY useful for development when combined with:
python -m SimpleHTTPServer 8020

i.e. try this in the root directory of the repo:

    python -m SimpleHTTPServer 8020 &
    open -a Google\ Chrome http://localhost:8020/index.html
    ruby chrome_watcher.rb pages 'localhost:8020'

then every time you run `make html`, the chrome page will automatically
refresh!
Finish part 3.