Add Typelibrary.GetMethodsWithAttribute
Add ThumbnailRenderAttribute
Add IResourceCompilerContext.def
Add Asset.OverrideThumbnail( pixmap )
Prefabs have thumbnails!
https://files.facepunch.com/garry/b3633834-6291-42da-80d3-d51924e0a2fe.png
Move ThumbnailRendererAttribute