Switched from `autosave` to `autocomplete` in <input> elements

@devoncarew 

`autocomplete` doesn't work as advertised either, but at least it's how preserving previously entered values is supposed to be done (`autosave` was completely wrong: it's only for `<input type="search">`, and is barely supported by browsers).

I'll file a bug about `autocomplete` not working right after landing this.