* reduce heap allocations in tcp logging; omit use of AppendFloat which allocates a metric sh*tton
* debugheaplog: better heap statistic logging
* heap: use string for pcap.Frame.Protocol
* add potential to eliminate Flags.String heap alloc, remove incorrect HEAP comments
* add StackAsync.DebugErr and httpraw.SetBytes
* many heap alloc reductions and replacement of bytes.Equal with internal.BytesEqual
* claude suggests a way forward
* add timing to capture printer
* add pcap.Flags
* fix ICMP CRC calculation and add test
* bugfix: still send data on half-close state(close-wait)
* fix pcap test
* do not rely on unspecified Go behaviour; fix TCP ring buffer bug
* even more stricter error handling on tcp connections
* stricter lock copying in tcp.Conn, even though likely not a problem
* add listener and tcp pool logging
* forgot reqAddr unused
* add logging to TCPConn and friends
* 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