Dataset collections - abstraction for collection types.

Perhaps over-engineering but want to centralize logic for reasoning about what kinds of collections are subcollections of other types, etc....
Dataset collections - hide HDAs behind implicitly mapped HDCAs.
Dataset collections - workflows - argument extraction for implicit mapping steps.

Second try at this.... I am not saying this good, but it is better than me previous attempt.
Dataset collections - augment workflow extraction for copied/imported dataset collections.
Dataset collections - workflows - collection parameters, inputs, and map/reduce in editor.
WIP;:Anonymous users, still need to handle dataset permissions in dataset collections.