Add a way to suggest using the user's last submission description

[sheodox]

If someone is reading through a book and it takes them a few days or reading sessions there's a pretty good chance that the description used for the last submission still applies. It would be nice to allow the user to just click something to auto-fill the last submission's description so they don't have to copy/paste or re-type a possibly long book title.

Just populating the description box on click would also give them the chance to tweak it a little (like adding a percent complete, or changing the volume number). I could see users forgetting to change things if it were auto-filled, which is why I think it would be best to require at least some action by the user. I'm open to change here though.

This should probably be specific to the contest, as there's a pretty good chance a user won't be reading the same thing in contests a month or more apart. This should also be tied to the medium as if you log something as a book we can assume if you later log lyrics that you didn't read the thing you said was a book before.

Storing it in localStorage would prevent having to do an additional API call when viewing the ranking page, and it should be more or less accurate for users who use one device, or frequently use a couple.

Just messed around in dev tools to make this. Not sure exactly what it should say or look like or say, but this is the general idea I had in mind.