Implement fast SLERP.
Raise the changed event in CzmlDataSource when CZML is loaded.

Also clarify the documentation in DataSource to indicate that the changed event should be raised when the name or clock changes.
Some tweaks for performance testing.
More performance tests.
Remove performance tests. Use fast slerp implementation with typed arrays. Add one more test comparing with old slerp implementation.
Add fastSquad that uses fastSlerp, tests and doc.
Add an option to control whether the first data source added to Viewer automatically sets the clock.

Also improve the logic so that changes to the clock afterward, indicated by the DataSource changedEvent, update the clock as well.  Fixes #1134.
Don't fire changed event in CzmlDataSource unless clock or name have actually changed.
Update CHANGES.md
Replace getElementsByTagName with a case-insensitive regex to search for TileFormat
Merge remote-tracking branch 'origin/master' into fixDataSourceChanged

Conflicts:
	CHANGES.md
Merge branch 'master' into fastSlerp
Update CHANGES.md.
Add regex search for TileSets as well
Use fast functions by default for quaternion spline. Update error tolerance in tests.
Fix #1336 by adding a master kill switch for inputs.
Fix Cesium.js generated file.

My recent changes to generate stubs caused the fileset for Cesium.js to be created too early, meaning that shader files could get left out if they were not present on disk before the build started.

Instead of the pathconvert hackery I was using before, I fixed our custom scriptdef tasks to work with file-based ResourceCollections instead of requiring a FileSet, so that we can use the <union> directly.
Merge pull request #1370 from AnalyticalGraphicsInc/fastSlerp

Fast SLERP
Merge remote-tracking branch 'origin/master' into fixDataSourceChanged

Conflicts:
	CHANGES.md
Handle casing differences in XML