[Seaside] Template system for Seaside + docs

[Julian Fitzell]

Avi Bryant wrote:
> There are a few advantages to this.  One is that rather than the 
> massive, monolithic renderer API, you get the methods split into more 
> focused classes (all the variations on #tableRowWith:, for example, 
> would just be on the Table node).  Another is that if you have a generic 
> #add:, you can start doing stuff more functionally:

Hmm... I wonder how well you could implement this with only single 
inheritance and no mixins... :S

I'm pretty sure the rules for what elements can be contained in other 
elements, etc. aren't going to map very well to a single inheritence tree...

Julian