Changes

Configuration for mainWs sending pools (#776)
This allows to share threads between shards for main ws sending queue
workers. Since these threads spend most of their time sleeping it makes
sense to allow sharing resources between shards.

* Improve ThreadFactory name consistency
* Make use of queue lock for all parts of the send system
* Switch to ScheduledExecutorService for rate-limit pool
* Use life cycle pool to close audio connections
* Remove unnecessary thread group
 (commit: 5b50c18)