* begin reviewing TCP listener
* begin adding listener tests
* adding TestExchange implementation
* split out legacy and Step tests
* move listener to tcp package
* fix up tcp tests taking very long
* add xnet.TCPPool and work on TCPPool semantics
* xnet: TCPPool only accepts established connections
* xnet: getting to bottom of panic in xnet.Listener
* xnet: improve listener tests
* fix several data races in testing fixtures
* fix more synchronization things in listener test
* finalize tcplistener test
* add prints to investigate slowness
* add loop sleep for blocking Stack
* add connection close http attribute and detect end of HTML page
* add timeout to bridge read
* examples/xnet: add ntp timestamp to prints and show output in readme
* add polling to http tap interface
* more digits in ntp format
* prevent crashes on non-8 timestamp
Pat Whittingslow