GitLab

* copyright headers

* isort and pyproject.toml

* precommit and requirement for isort-seed-config

* mypy

* dummy change

* numpy version for pre-commit

* fix mypy issue caused by numpy
Co-authored-by: Min Xu <min.xu.public@gmail.com>

Adds support for:
* Reused layers (e.g. for weight sharing)
* Lazily-constructed layers
* Single-process control via PipeRPCWrapper
* PipelineStyle.AsyncScheudle, which lays the foundation for asynchronous pipeline work by introducing an event loop for each rank/worker to process either activations or gradients as they arrive

Also added examples for multi-process and PipeRPCWrapper