In-VM pipe support which removes the overhead of local loopback communication.

# What is 'in-VM pipe'?

In-VM pipe is a direct event forwarding mechanism between two `ProtocolHandler`s in the same Java Virtual Machine. Using in-VM pipe, you can remove the overhead of encoding and decoding which is caused uselessly by local loopback network communication. Here are some useful situations possible:

- SMTP server and SPAM filtering server,
- web server and Servlet/JSP container.

Please refer to Tennis example.