Make the AddFilterDialog a GtkWindow
Tweet: Use an array to store the urls

And at the same time, introduce a 'sorted' parameter to TweetUtil's
get_formatted_text and get_real_text so the urls don't get resorted at
every call
ProfilePage: Don't turn on notifications for new followee
AddFilterDialog: Add more layout widgets
AddFilterDialog: Add content entry label
Tweet: Add get_urls function
MainWindow: Correctly initialize the size of the pages array
filters: More ui code