Clean up BaseScenes and Objects info structs

[benjamin-heasly]

Currently, the example BaseScenes and Objects assets are copied directly from an older repository. See initial import script.

The metadata for these assets is out of date, since much of the same information can be gathered from the mexximp scene struct. Also the mexximp scene struct is based on the types and names of scene elements, whereas the old metadata uses Collada element ids which were produced by Blender and not portable.

So, update the example BaseScenes and Objects info structs to remove redundant info and avoid Blender-Collada-specific ids.