v2.1 released, discord experiments

Bepuphysics v2.1 has been released and pushed out to nuget packages. It includes all the accumulated changes since release- nothing groundbreaking, but lots of small improvements, convenience features, and bug fixes.

At the request of some users, I’ve also created a discord as an experiment. I will still focus on the forum/github for long-form content, but I will pop in occasionally.