Cleanup

I put both a title and a description in almost all of the commits (click the ...) which explains the rational.

The big changes are:

- Using CSS to do the fade in / out.  That way it will be smoother, and you don't need to write the code, which is always nice.
- Fixes which will make this play nicer with other scripts on the page.  A big thing we've learned in recent years as more and more javascript ends up on pages is how important it is to not accidentally interact with things you don't intend.
- It now just won't show up on IE8, because maintaining compatibility is a pain, and probably isn't necessary.  Very few people outside of China really use IE8 anymore.