Serge documentation goes live

The first version of the documentation for the serge engine has gone live.

This is the documentation of the core engine only and covers just the main classes and structure. I also need to document the blocks and the tutorial. 

I used the Sphinx documentation system, which seems very powerful and easy to use.  You can quickly generate useful documentation with a nice look and feel. I would like to change the overall template to look more like the rest of the site but for the moment it works well.

Once I get the blocks documented I will start to try to use that in my own development to road-test the documentation itself.