Cleanup quadtree space

[Yomguithereal]

Currently, the quadtree indexes the framedGraph space, normalizing the sizes by the container width. This works but is conceptually weird and might cause issues with screens having a vertical aspect ratio.

We could use the nullCamera viewport space to index but there are two issues with this:

1. Handling rotations
2. We would be wasting some part of the x or y dimension (we already are actually), since we rescale the graph aspect ratio wrt viewport aspect ratio.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[jacomyal]

Once #1382 is dealt with, this issue will be solved.