Edit metadata, unread book list, bookmarks ordered by place not time

I've added metadata editing for Authors, Tags, Titles, and Series. This is my first pull request, please let me know if I'm going about this wrong.

I also added a list of books labelled unread (similar to favorites) and changed the order in which bookmarks are displayed so they are in order of position rather than when they were added. 

For the unread list, I did need to add a new string which is not translated to the other languages... I don't know what to do about this. I'm also working on a rooted device and don't have another to test on and I don't know if new problems will come up on a non-rooted device.

Thanks,
Sarah