Website update and code release!

After four years of a stagnent website, I've finally updated the website! Having been through significant changes in group membership, many updates in our research directions/output, not to mention a global pandemic, I thought it was about time! In addition, we've just released our development code, called 'vayesta', which focuses on accurate and improvable approaches to ab initio quantum embedding. This has really been driven by Max, with important contributions from Charlie, Ollie, Alejandro and Basil. Hopefully it will be of wider use - check it out now by looking at our documentation here! Congratulations to all involved!