Deletion message could be more useful when a box has clones

[sandbergja]

Steps to recreate:

• Create a box
• Clone it in a different guide
• Try to delete the original. Note that you get a message "This box cannot be deleted because it has linked boxes. [name of the other box]"

In my case, the linked box had the exact same name as the original box, so it really didn't add much info to go on. Two improvements that would be helpful for me:

• A link to where the clone can be found, so that the user can see it in context and decide what they want to do with it.
• Maybe, for those that want to live dangerously, an option to delete the original box and the clones, all in one fell swoop.