basic: track URLs, payload types and UDP ports are hard-coded #40

On basic, rtsp_connect() ignores the SDP:

• SETUP always goes to <url>/trackID=0 and <url>/trackID=1, whatever a=control says.
• Payload types are fixed: 96/97 video, 100 PCM audio, 98/99 ignored (processPacket).
• In UDP mode the client asks for client_port=5000 (video) and 5002 (audio), but only port 5000 is opened, so UDP audio never arrives. A fixed port also clashes with anything else on the device that uses 5000.
• The audio SETUP is sent even when the stream has no audio track; its reply is read but not checked.

Fix: parse the SDP (a=control, a=rtpmap) as v2 does (#9 and #19 for the remaining gaps), and use ephemeral UDP ports, or drop UDP on basic.