[Scenario] Listen for staleness with temporary object

When rebuilding a timeline view, use a new
listener object for tracking staleness. This
supports resolution of nasa/MCT-Plugins#80;
direct cause of the latency was that a
large number of listeners were being fired
from old activity views that were no longer
showing.
[Scenario] Address component memory leaks

Address component memory leaks which were
contributing to latency issues. Specifically:

* Clear out constraints when rebuilding a
  timeline view (due to staleness, for
  instance.)
* Remove change listeners registered by
  timeline controls when appropriate
  ancestor has been removed. (The absence
  of this was causing old components to
  be exempt from GC, by way of listening
  Graph views which were showing those
  old components.)
[Scenario] Verify staleness to avoid update cascade
Merge pull request #82 from VWoeltjen/staleness

[Scenario] Resolve latency on repeated Save All