The mod_websocket continuation-frame patch accumulated fragments in an
unbounded dataBuffer with no size limit, fragment count limit, or
timeout. A buggy or malicious client sending endless continuation
frames without FIN could exhaust memory and degrade the entire server.
Add a configurable websocket_max_message_size option (default 2 MB)
that closes the connection with code 1009 ("Message too big") and
resets the buffer when exceeded. Also add wss-perf-analysis.md
documenting the WebSocket performance and drop investigation.
Part-of: <http://gitlab.vnc.biz/uxf/vnctalk-prosody/-/merge_requests/8>
