Update the sky box to use the correct orientation.

Also added a `skyBoxBaseUrl` parameter to the widget, for easily
swapping out different sets of SkyBox images.
Merge pull request #488 from AnalyticalGraphicsInc/stars

Update the sky box to use the correct orientation.
Update erosion picking example.
Merge pull request #491 from AnalyticalGraphicsInc/pickingExample

Picking Example
Merge remote-tracking branch 'origin/master' into terrainRefactoring