consider removing SEDA pipeline from mix server

[david415]

There might be a few advantages to having the mix server be a simple thread pool of workers instead of the series of thread pools connected together in a pipeline (Staged Event Driven Architecture). On such advantage is fewer places in the code where packets are dropped.... which might mean a negligible performance hit because the packet might not get dropped as soon as with a SEDA pipeline.

[mixmasala]

There might be a few advantages to not rewriting something that works.