… replaced with public property
The CesiumViewer app is now built into its own layer instead of using dojo/dojo.js. Rename boot.js to CesiumViewerStartup.js and move all code out of there. It only exists to set up the package config. Reduce the number of files in the built output by deleting stuff we don't need, and modules that are already included in the app layer.
Also added a `skyBoxBaseUrl` parameter to the widget, for easily swapping out different sets of SkyBox images.
Previously the files to be copied were whitelisted, but it should be the other way around. This now correctly pulls in the needed XYS data files.