The stream connector replaced the conn_stream and the sc_conn_io_cb()
function appeared. There's no place there to mention the endpoint
descriptor, but a separate diagram showing the relation between stream
and endpoint via the connector would be nice.
Since the muxes API is far from being obvious, let's show a stream being
forwarded between two sides through muxes with their buffers and the
transport layers. The diagram is provided in .fig, .svg, .png, and .pdf.