0fdc0f8bbd
The idea is following: we do need to have multiple dependency graphs to denote different scene layers (depsgraph should only contain objects from a specific scene layer), and we also want to support same scene layer to be evaluated to a different state in different windows. In order to achieve that we do need to have a list or hash (for faster lookup presumably) somewhere. To keep things easier for now, it will be a scene which owns that hash. This seems to make sense anyway, since dependency graph only points to data which is owned by scene. This commit only introduces some basic API and hash itself stored in DNA, there is no changes in behavior. See this as a first step towards getting rid of scene-global dependency graph.