Netty nested pipelines / multiplexing

There is no support for "nested Pipelines" yet. It may be part of 4.1.0. For now you need to remove/add handlers on the fly.

See [1] for an example.

[1] https://github.com/netty/netty/blob/master/example/src/main/java/io/netty/example/portunification/PortUnificationServerHandler.java