Prevent/detect render cycles

[MondayHopscotch]

Jake ended up with some weird stack overflow exceptions that we didn't uncover the cause of. However, they certainly had to be caused by cycles in the render graph. Clean up how the graph is built and better understand how this can happen.

[MondayHopscotch]

Managed to get a call depth exception that had to have come from the render graph having a cycle in it. Happened as I pushed a block in front of another one.

Figure out a good way to manage the render graph and mark things as dirty efficiently.

Ideally, we have a way to manage the graph only for the things that move so we don't have to sort the entire scene every time something changes.