Add INetworkManager for diff visibility
Spigot patch: 0026 Netty

Implement an uber efficient network engine based on the
Java NIO framework Netty. This is basically a complete rewrite of the
Minecraft network engine with many distinct advantages. First and foremost,
there will no longer be the horrid, and redundant case of 2, or even at
times, 3 threads per a connection. Instead low level select/epoll based NIO
is used. The number of threads used for network reading and writing will
scale automatically to the number of cores for use on your server. In most
cases this will be around 8 threads for a 4 core server, much better than the
up to 1000 threads that could be in use at one time with the old engine. To
facilitate asynchronous packet sending or receiving (currently only chat), a
thread pool of 16 threads is kept handy. == Plugin incompatibilities As a
side effect of this change, plugins which rely on very specific
implementation level details within Minecraft are broken. At this point in
time, TagAPI and ProtocolLib are affected. If you are a user of ProtocolLib
you are advised to update to the latest build, where full support is enabled.
If you are a user of TagAPI, support has not yet been added, so you will need
to install the updated ProtocolLib so that TagAPI may use its functions. ==
Stability The code within this commit has been very lightly tested in
production (300 players for approximately 24 hours), however it is not
guaranteed to be free from all bugs. If you experence weird connection
behaviour, reporting the bug and steps to reproduce are advised. You are also
free to downgrade to the latest recommend build, which is guaranteed to be
stable. == Summary This commit provides a reduction in threads, which gives
the CPU / operating system more time to allocate to the main server threads,
as well as various other side benefits such as chat thread pooling and a
slight reduction in latency. This commit is licensed under the Creative
Commons Attribution-ShareAlike 3.0 Unported license.

https://github.com/EcoCityCraft/Spigot/blob/d9c76252eb02f7d0d6bea11efe77e3bb1edb0d99/CraftBukkit-Patches/0026-Netty.patch
Add throws to NettyServerConnection constructor for MCP compatibility