Adun 0.81

These are the release notes for version 0.81 of the Adun molecular simulator. It's been a while since the last release, and in addition to the changes listed below v0.81 contains fixes for far too many bugs to mention, and numerous small user tweeks. The new version also sees assorted changes "under the hood", the benifits of which will be gradually made apparent over the rest of the 0.8x release cycle.