fixed an Error where the AnchorlineColor reused the given color

[jbo023]

AnchorLineColor in the Vector3DTilePoints is using a scratchColor to set the Color to the Cesium3DTilePointFeature. This only works when the function clones the Color, otherwise all colors take the value of the last feature.
https://github.com/AnalyticalGraphicsInc/cesium/blob/master/Source/Scene/Vector3DTilePoints.js#L425

[cesium-concierge]

Thanks for the pull request @jbo023!

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• Cesium Viewer works.
• Works in 2D/CV.
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[lilleyse]

Thanks @jbo023, the fix looks good to me.