Node graph experiment

[philstopford]

I've wanted a node graph component in/based on Eto.Forms for a while now. Lacking the time and talent, I asked Copilot for some help and it came up with this. It seems to work pretty well so far and I thought I'd mention in here in case others might find it useful or choose to expand it, etc.

https://github.com/philstopford/Eto/tree/copilot/add-node-graph-component

There's a sample project that shows geometric processing, and there's a simple calculator node graph as well.