Cleanup CSS in Hello World.
Properly clear gutter markers in Sandcastle

I was using `clearGutter` incorrectly, which resulted in the problem.
In order to match the old behavior, we now declare 4 gutters and clear them
out as needed.
Further simplify the CSS in Hello World.
Merge pull request #2228 from AnalyticalGraphicsInc/sandcastle-gutters

Properly clear gutter markers in Sandcastle
Add parameter to BingMapsImageryProvider to allow changing the culture of the imagery.
Fix QuantizedMeshTerrainData test failure.
Update CHANGES.md
Add readonly to doc.
Merge pull request #2230 from AnalyticalGraphicsInc/bingCulture

Add parameter to BingMapsImageryProvider to allow changing the culture of the imagery.
Add missing readonly doc
Merge pull request #2231 from AnalyticalGraphicsInc/quantizedMeshTestFailure

Fix QuantizedMeshTerrainData test failure.
Merge pull request #2226 from AnalyticalGraphicsInc/hello-css

Cleanup CSS in Hello World.
Merge pull request #2232 from AnalyticalGraphicsInc/readonly-imagery

Add missing readonly doc to imagery providers
Fix translucency by distance decompression.
Merge branch 'master' into billboardCompression