Need to be able to release collections of nodes that are no longer required.

[alecmce]

We reference collections of nodes in a system using

System.onRegister { nodes = game.getNodes(NodeClass); }

we should probably do the inverse in onRemove, or at least offer the functionality:

System.onRemove { game.releaseNodes(nodes); }

This functionality would probably actually sit in NodesManager.release

[richardlord]

That sounds like a good idea. You'll want reference counting on the collections in case multiple systems use the same collection.