State state demarcation

"Wat?"

So this thing was built to re-create a router like the one that Ember provides. One feature of Ember's router is that states themselves can have unique state. This might seem crazy, but lets consider the following state, `books/book`. The route for this state might be `books/:bookId`.

This state can have any number of unique states based on what ID is passed to it. For instance, `books/2` is distinct from `books/3`. Therefore, if a user goes from `books/2/authors` to `books/3/authors`, it should reload that book. Right now, hsm will just say, 'nothing has changed' for the `books/book` state, which is inaccurate.

The same problem happens if you were to transition between different child states, like `books/3/authors` to `books/2/comments`. It should realize that the second state's 'state' is different, and that things need to be set up again.

No files, tests, or entry points are named. Start by tracing how hsm compares the current and target states during transitions, using books/2/authors to books/3/authors and books/3/authors to books/2/comments as cases. Done means distinct route parameters cause the affected state and its children to be set up again.

Written by the indexing model from the issue text.