Removed PHP extension from URLs

This commit works fine, i.e. no errors and routes everything properly.

Unfortunately, without using something a PHP router, I don't think we'll be able to use the 301 redirect technique.

If that's something you want to do, we can look into it. Otherwise, I don't think the 301s will be that important anyway. The old ```*.php``` extension URLs will still work perfectly, but now the pages point to the URLs without the extension, meaning the ```*.php``` will slowly be replaced in page rank by the new form.

I refunded the last commit tip because it didn't work and it felt wrong to me to get paid for a bad contribution, tx: https://blockchain.info/tx/955d9ed2a1469fcb8f0b9a9240d193e1292590380840c3cf177d6a9b194c8e6c

Hopefully this one works just as well as the last one I intended to.