Improve stat pages

Stat pages are a complete shitshow exposing how bad I was at mysqling things 10 years ago (not saying I've really improved in that area :)

Problems:

1. Code has been ugly for years

2. Code doesn't easily allow smarter plugins to take over (I think that's probably a reason why there are no stats plugin)

3. This page is pulling every info from the DB in a few queries then doing PHP stuff to rearrange and display. While this is fine for a couple thousand hits, it quickly becomes completely unpractical, if not just failing, when days and/or hits add up.

4. This page displays just everything. Again, why not for a couple hits, but this has probably no value to anyone:

Maybe we should have a more simple page and have the "details" loaded on demand by ajax.

Any suggestion or PR welcome.