Issue#90 and PR#96 sought to promote Netty from the testing directory to normalsrc/main/java code.

As detailed in#96 I was historically reluctant to do this because of intermittent issues with Netty. Eventually I investigated these issues and corrected them in#133. As this was almost a year ago and I haven't seen any issues in any builds since then, I assume the fix worked and it's safe to promote Netty out of test as a result.