Add a more complex feature

[kylecordes]

So far all of the example routes/features here are pretty simple. Add a more complex one, with more components interacting.

The purpose of this is to understand and demonstrate in more instances, how components are coded and how they interact with minimal boilerplate.

This new feature should share state across a "tree" of related components, not only between adjacent (parent/child) components. The sort of need comes up often in real life complex applications, but will require some thought for a small but motivated example to include here. Something that can be coded in a few hours, not weeks or months.

(I initially thought of including a TodoMVC, but there are already several of those for Cycle.)