* 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
* chore(crates): updated crates to Bevy 0.13
* updated deps
* updated / changed code where relevant
* updated README files
* bumped version numbers for upcoming release
* updated rust-toolchain
* updated assets where relevant
* closes#132
* feat(bevy_gltf_components):
* added GltfProcessed flag component to improve performance of iteration over added<gltfExtras>
* closes#144
* light & shadow processing is now integrated, to match lights coming from Blender: you can now control whether
lights cast shadows, the cascade resolution , background color etc from Blender
* closes#155
* feat(bevy_registry_export): added boilerplate to make registry path relative to assets folder
* closes#137
* feat(tools): added boilerplate for internal tools
* clean zip file generator for blender add-on releases
* example gltf file generator
* feat(lighting): added components, exporter support & testing for blender-configurable shadows
* added BlenderLightShadows component to bevy_gltf_components
* added writing shadow information to gltf_auto_export
* updated tests
* closes#157
Co-authored-by: Jan Hohenheim <jan@hohenheim.ch>