temporary fix for #issue746.
Merge remote-tracking branch 'origin/master' into issue746
Added clipToWindowCoordinates
Added fromElements
Updated CHANGES.md
Added wgs84ToWindowCoordinates
Removed Polygon.computeScreenSpacePosition
Cleaned up Billboard actual position
Added doc
Added missing doc
Merge master to issue746
Merge remote-tracking branch 'origin/master' into issue746
Merge master to issue746
Cleaned up CHANGES.md
doc and tests for SceneTransforms, fromElements in Cartesian2, Cartesian3 and Cartesian4.
Merge master to issue746
More changes after review.
Fix whitespace and one last typo.
Merge pull request #750 from AnalyticalGraphicsInc/dataSources

Data source abstraction
Change buildModuleUrl to always return an absolute URL.

Fixes #779.