Rename ExtentTessellator to ExtentGeometry.
Remove unused code.
Change ExtentTessellator to be ExtentGeometry (computes positions only).
Add texture coordinates to extent geometry.
Add normal, tangent, and binormal vertex attributes to extent geometry.
Remove 'configureExtent' from Polygon. Revert CesiumViewer.
Update doc and tests for extent geometry.
Compute bounding sphere of an extent at a height above the surface.
Update CHANGES.md.
Throw exception when extent is not given. Add test.
Merge branch 'batching' into extentGeometry
Change Extent.subsample and BoundingSphere.fromExtent3D to use a height parameter. Add tests. Update CHANGES.md.
Updates based on review.
Tweak CHANGES.md
Merge pull request #787 from AnalyticalGraphicsInc/extentGeometry

ExtentGeometry
Merge branch 'batching' into computeTangentBinormal

Conflicts:
	Source/Core/EllipsoidGeometry.js
minor fixes