Add 'bsml_queue_count()' to return the number of items in a queue.
Use a pthread lock when modifying a queue.
Add 'bsml_copy_string_len()' to copy a portion of a string.
Enhancements and code tidyup to WebSockets streaming: run a stream as a separate thread; check for a full receive queue; create WebSocket as part of a new data request and don't separately create a 'stream'; use v1.2 libwebsockets API; etc.
Rename 'bsml_stream_reader' to 'bsml_streamreader' and provide a '_free()' method for structure.
Provide text for BSML_STREAM_ERROR_NO_CONNECTION.
Check for, and close connection, if memory is exhausted.
Disable NOTICE logging from libwebsockets.
Return space remaining from bsml_queue_put().
Closedown stream if the receive queue fulls.