This mainly extracts a new module called
browser_history. It has much fewer dependencies
than hashchange.js, so any modules that just
need the smaller API from browser_history now
have fewer transitive dependencies.
Here are some details:
* Move is_overlay_hash to hash_util.
* Rename hashchange.update_browser_history to
brower_history.update
* Move go_to_location verbatim.
* Remove unused argument for exit_overlay.
* Introduce helper functions:
* old_hash()
* set_hash_before_overlay()
* save_old_hash()
We now have 100% line coverage on the extracted
code.
Steve Howell