Boost/Asio built in single-threaded mode. This is done due to the
revelation that Asio socket objects are not thread-safe.
Break out IOStats into two classes:
* IOStatsSingleThread
* IOStatsMultiThread
* test/cascli -- call AS client API from C++ by embedding python
* test/embed -- misc test code for embedding python
* test/dtls -- DTLS proof-of-concept code
* test/tunflood -- test boost::asio wrapper around linux tun/tap device