Improve performance

[hobnob]

Is your feature request related to a problem? Please describe.
Adding to the DOM is just slow - we can do better

Describe the new feature you'd like
As it stands any change to the board requires Elm to parse the entire tree for differences and add it. This results in a second or so of delay. It's not the biggest issue in the world, but it still annoys me and needs changing. We can be faster, we should be faster 🙂

This will involve lazy loading where needed, and correct DOM keys set where appropriate for pieces that may move a lot.