New features

• Brand new, independent, and lighter weight package

Breaking changes

• Supports Node v8.9.0 and higher
• No longer supports a callbacks for named Web API methods, or the RTMClient.sendMessage() method.
• Removed the raw_message event in favor of the slack_event event.
• agent option has been simplified
• Some ErrorCode constants have changed.
• Support Logger objects without a logger function.

See the migration guide for details.