closes: #43 (closed)
Added better error handling when editing a story and trying to play a story. When editing a story title, the user is now not notified before the text field is unfocused. When trying to play a story, the story will check if the story is playable. When removing a passage, the passage will not be deleted if there are any links to it. When starting a story, the user will be notified if there are any broken links in the story.