Delete dialog's delay animation.

[simjanos-dev]

On some delete dialog's there is a delay animation so the user cannot delete things accidentally without reading the dialog. It is done with multiple setTimeout calls, but should be changed to css animation and one setTimeout call to make sure it takes the same time on every client.

[cblanken]

I like the delay animation, but if you really want to make sure people read the action description, it might make sense to replace the delay with a text box that requires the user enter the title of the book/chapter they're deleting. Sort of the like the prompt for deleting a GitHub repo.

That might be too heavy-handed though. Just a thought.