First draft of template engine chapter

I've added myself to the table of contributors, but I have a few questions about the information we're choosing to present.
Do you think it would be possible to discuss these features incrementally, possibly alternating between "here is why you might need this feature, and here is how we implement it?" (I haven't read ahead yet, so it's possible that your implementation takes care of several "layers" of these at a time)

Alternately, it might be easier to do an up-front feature list like this if you present a short, full example of a template that incorporates all of these features at once. You could then show a sample context for the template, and the end result of the template substitution, discussing in turn how each of these features made it possible to generate that content.