Provides Django Channels channel layers that use Redis as a backing store.

There are two available implementations:

RedisChannelLayer is the original layer, and implements channel and group
handling itself.

RedisPubSubChannelLayer is newer and leverages Redis Pub/Sub for message
dispatch.  This layer is currently at Beta status, meaning it may be subject
to breaking changes whilst it matures.

Both layers support a single-server and sharded configurations.
