Initial rewrite.
Somewhat working

Can run a server as a test, but it throws exceptions when it closes.
Might want to implement channel from scratch.
New channel implementation.

Might be better served by making it a child class of ChannelMultiplexer.
That way we can remove the ChannelOps class at the cost of a larger
ChannelMultiplexer definition.
Small refinements of the Spdy multiplexed encoder