Provide mechanism for active screen to update history.

[dpup]

A screen may contain multiple tabs that can be navigated to directly. When changing tabs, without doing a full navigation, the history state should be updated accordingly. It should also be possible for a cached screen to match multiple paths it can display, rather than a single path at present.

e.g.
photos/dpup/ -> photo screen.
photos/dpup/recent and photos/dpup/popular are filters on the photo screen.