Upgraded to Silverstripe 2.4.0

This website has just been upgraded to Silverstripe 2.4.0, which adds (amongst other things) hierarchical URLs. While the effort has been worth it, this upgrade was more problematic than previous ones due to version 2.4 including a cleanup of the API, and some rather major changes. Fortunately I now have a test server that I can do trial runs on before making changes to the live website. Here's a quick rundown of the problems that I experienced, and the solutions.