Start creating a very simple CesiumWidget to replace the Dojo-based one.
Switch Sandcastle examples to new standalone CesiumWidget.
Merge branch 'master' into cesium-widget
Merge remote-tracking branch 'origin/master' into cesium-widget

Conflicts:
	build.xml
Merge branch 'master' into cesium-widget
Move CesiumWidget into its own subdirectory to be consistent with other widgets.
Some minor widget tweaks.  Major changes to come.
Merge branch 'master' into cesium-widget
Cache DrawCommands in BillboardCollection.

Addressed issue #550

This seemed easy enough so I took a stab at it.  I kept it simple so we cache only as many as we need and discard them when we don't.
We could have a separte pool (or a generic ObjectPool) implementation if we want something more sphisticated, but I wasn't sure if the overhead was worth it.

What do you think @pjcozzi ?
Fix Billboard.computeScreenSpacePosition.
Update CHANGES.md.
Merge branch 'master' into computeScreenSpacePosition

Conflicts:
	CHANGES.md
Small JulianDate cleanups.

* Use a scratch variable for leap second lookups instead of allocating.
* Add an instance compareTo method, use that from LeapSecond.compareLeapSecondDate
Fix a number of places that were using reference equality on JulianDate instead of equals.
Fix typo.
Merge pull request #553 from AnalyticalGraphicsInc/billBoardDrawCommands

Cache DrawCommands in BillboardCollection.
first pass at terrainSample contrib
fix formatting issue
Fix inconsistent name of cache variable
Merge pull request #558 from AnalyticalGraphicsInc/fixDateComparisons

Fix date comparisons to use equals