- upgraded to Blender 2.91

- added compositor-rendering support for accessing different render passes. See examples.
- moved gamma correction from renderers to btb namespace
- added functional materials for rendering camera-space normals
- fixed unit tests failing for control tests

updated wording

blendtorch v0.2

- Support for training RL agents in OpenAI environments defined in Blender. See `examples/control` for details.
- Support for dataset transformations when `num_workers > 0`.
- Support for message recording when `num_workers > 0`.
- Made `blendtorch.btb` and `blendtorch.btt` installable packages. See `Readme.md` for details.
- Remote data streaming now uses PyTorch IterableDataset and
hence simplifies the interface. See `examples/datagen` for details.
- Added unit tests and CI.

Merge branch 'release/v1.0'