handle actions that require saved entities

Quite some actions can only work with entities that are already saved. We need to improve our intelligent saving mechanism to save newly created entities that are passed to such actions *before* we can move on.

If the entity is under creation but is not marked to be saved by rules, saving is probably handled otherwise (consider presave during entity creation) and we cannot do anything about it - thus this case should trigger a rules warning and abort evaluation.

Any ideas about a good key for an action parameter to denote a saved entity is required?
Maybe 'require id' => TRUE ?