Make it possible for named routes to be generated on the fly.

To demonstrate this, you can now long-press a stock to open it.

Next steps:

 - transitions between (named) states that follow full material logic,
   e.g. in the case of the stock row to stock page transition, expanding
   the row into a raised sheet of material and expanding it to fit the
   screen, leaving the toolbar in place but cross-fading the old
   contents to the new contents.

 - more information in the stock view.

While I was here I also made Material have an opinion about default text
style, so if you forget to set one, it just uses body1.

Also, fixed bugs introduced recently that made RouteState and MenuRoute
not work properly.