generative geometry and shadows

generative and gpu instantiated geometry seemed easy, though I always wanted to be able to add shadows to the scene. For me this was an interesting project to learn about deferred lightning and unity's rendering pipeline with its command buffers.

feel free to use this code as you wish, any contributions and pull requests are welcome. Tested on Win10 with unity 2019.2.0.a14.

thanks

keijiro and przemyslawzaworski and their snippets were very inspirational, but this thread by CustomPhase helped quite a bit.