* Added symmetric encryption for messages and at-rest data with key rotation.
0.11.0
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* Implement backpressure with per-channel and default capacities.
0.10.0
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* Group expiry code re-added and fixed.
0.9.1
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* Remove old group expiry code that was killing groups after 60 seconds.
0.9.0
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* Connections now pooled per backend shard * Random portion of channel names now 12 characters * Implements new ASGI single-response-channel pattern spec
0.8.3
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* Nonblocking receive_many now uses Lua script rather than for loop.