Allow users to see how other worlds have been created

[bashybaranaba]

Allow users to see how other worlds have been created - i.e. Allow them to view the node diagrams of created worlds.
The goal behind this is to make users recreate and customize/personalize worlds they find intriguing.
Let world owners decide if other users can view their world node diagrams - possibly in the publish dialog.(include small explanation in a hover card)