API audit WRT Rend3

[schell]

It would be nice if I could provide folks with a migration guide from Rend3. Here's the API https://docs.rs/rend3/0.3.0/rend3/struct.Renderer.html.

[John-Nagle]

Looks good. Let me know when things are far enough along that I can port my test program, render-bench. Thanks.

[schell]

Ah, I see now! Disregard my previous comment in another thread. I'll let you know when this is underway.