Continue rotating after mouse does not pick the globe.
Activate model animations when loaded via CZML

Eventually we will allow compelte animation control via CZML, but for now we can simply activate all animations so that wheels always spin and propellers twirl.

Also ran sortRequires.
Fix PathVisualizer

PathVisualizer was not handling the case when a DataSource is added to the display and it already has entities in it.  While reviewing the other visualizers, I also noticed that Geometry and Path were not unsubscribing from the collectionChanged event.
Add tests for bugs fixed.
Merge pull request #2004 from AnalyticalGraphicsInc/fix-pathVisualizer

Fix PathVisualizer
Merge pull request #2003 from AnalyticalGraphicsInc/czml-model-animations

Activate model animations when loaded via CZML
Merge pull request #2002 from AnalyticalGraphicsInc/camera-rotate

Continue rotating after mouse does not pick the globe.
Remove unused documentation images.