alias cat smile to :3

BUR #33833 has been rejected.

create alias cat_smile -> :3

I keep forgetting that cat smile is not a tag, but it's the first thing that pops into my mind when I see a :3 face.

cat has 79k posts, :3 has 114k posts. If I do this alias then cat smile will show up above cat in the autocomplete.

The bulk update request #33833 (forum #319737) has been rejected by @nonamethanks.