[Templates] adding support for incremental output

[Perrin Harkins]

Myk Melez wrote:
> These numbers show an expected decrease in time to initial content when 
> using FLUSH, but surprisingly they also show a significant decrease in 
> overall time.

I suspect this has more to do with the way your browser works than 
anything happening on the server side.  Try timing it with a 
command-line tool like ab instead and I suspect you'll find little 
difference between the flushed and non-flushed.

- Perrin