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
Merge remote-tracking branch 'origin/master' into issue746
Update SceneTransforms.wgs84ToWindowCoordinates test.
Merge pull request #747 from AnalyticalGraphicsInc/issue746

ComputeScreenSpacePosition for polygon. Temporary fix for issue #746.