support transitions via browser's back/forward buttons

- until now we were still getting map redraw issues if people used the
browser buttons instead of the bar buttons for navigating
- dismiss keyboard when user hits return in text field
- also added a search bar button to the top of the search page (so that
users don't have to scroll to the bottom of a long search if they just
changed a field at the top)
Merge branch 'master' into gh-pages