Pub/Sub sockets working with SocketAsyncEventArgs

Tested an initial version of the pub/sub sockets using
SocketAsyncEventArgs using async IO. Removed the required 3.5 threading
library. Tried a few things with proto buf.

Still need to test performance and start using buffer pools for
networking. PackateProtocol with buffers might not be necessary since
there shouldn't be any pinning of the byte[] objects. Let GC take care of
them.
Cleanup - removed simple tcp sockets and old stuff
Tidyup - Pub/Sub sockets
Lots of tidyup and initial load tests