Align stream state management and update behaviour across connectors

[teocomi]

The Stream State

Contains information about a "stream card" such as if it's a sender/receiver, selected branch etc. But also information about its previous receive operation, so that we can update elements of future receives.

Our Connectors handle stream state and consequentially the update behavior in different ways.

In Revit, it's stored in the stream cards and then in the Doc's extensible storage.
In Rhino, it's stored in the stream cards and on the object themselves.
In CSI products, it's stored in an external text file as there are no native ways to store custom data on the objects or documents.

The Problem(s)

Because of these different implementations, we have slightly different behaviors across the connectors.
For instance, in Revit the update functionality is entirely dependent on the Stream Card, if this is changed, the update capabilities can break.
If a different branch is selected, and new objects are received, the previously received ones are deleted as the update logic detects completely different IDs.
If the stream card is deleted and re-added, no update capability is preserved as the IDs are lost.

Proposed Solution

To be discussed, but perhaps storing the IDs on the objects themselves where possible, seems to be the most flexible option. In Revit it would require overcoming some potential performance challenges.
A good time to tackle this would be together with DUI3.