Fixes and improvements
- RTSP source: fix authentication during SETUP, preventing 401s during automatic protocol switches (#392)
- RTSP source: support servers that send frames with a frequency lower than 1sec
- RTSP source: support sources with empty passwords (#395)
- RTSP source: support SSRCs with missing zeros (#396)
- HLS: add CORS header to all responses (#389)
- HLS: support paths with slashes (#381)