Byteps

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* Fix compatibility issue with tf2 + standalone keras
* Add support for tensorflow.keras
* Improve robustness of broadcast

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* Add DistributedDataParallel module for PyTorch
* Fix the problem of different CPU tensor using the same name
* Add skip_synchronize api for PyTorch
* Add the option for lazy/non-lazy init

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* Largely improve RDMA performance by enforcing page aligned memory.
* Add IPC support for RDMA. Now support colocating servers and workers without sacrificing much performance.
* Fix a hanging bug in BytePS server.
* Fix RDMA-related segmentation fault problem during fork() (e.g., used by PyTorch data loader).
* New feature: Enable mixing use of colocate and non-colocate servers, along with a smart tensor allocation strategy.
* New feature: Add ``bpslaunch`` as the command to launch tasks.
* Add support for pip install: ``pip3 install byteps``

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* First official release.