make InternalHandler a (functional) interface
replace some anonymous classes with lambdas
formatting for MeshyServer
break out some MeshyServer inner classes
break out meshy channel handler + formatting
upgrade to netty4

mostly the same, but some more notable differences are:

- shutdown should be less prone to hanging
- buffer pooling is handled solely by netty
- MeshyServers share a worker pool with their Meshy superclass
  (meaning about half as many worker threads)