listing.js: Calls update_actions when selecting a file. This is the new method in browser.js which updates the actions along the top. (Currently Listing still produces actions on the side, because the top actions don't work properly yet and I don't want to break the build).
browser.js: Added update_actions which applies properties to the actions buttons on the top. (Enables/disables them, etc). Added handle_moreactions - event handler for selecting an item in moreactions. Currently sets things up properly but doesn't execute any actions. Added Refresh function (new user action).