* coherence pass : "main" scenes & co renamed to "level" scenes & co
* auto export now toggled ON by default, but bailing out early if there are no main & lib scenes added
* UI improvement for adding level/lib scenes
* minor cleanups
* started docs for Blender Blenvy add-on
* started migration guide
* got rid of a few examples
* moved (for now, wip) all remaining examples under the Blenvy umbrella
* updated main README
* fixed issue with undeleted bin file when setting gltf export options for gltf/bin mode
* updated release tools (internal_generate_release_zips)
* moved main TODO to root of repo
* a lot of related prep work & cleanup