Fixes and improvements
- RTSP source: support cameras that use non-conventional Transport headers
- RTSP reader/publisher: strictly follow the specification when generating SDP of AAC tracks (#112)
- RTSP reader/publisher: add SSRC to Transport header (#380)
- HLS reader: skip packets that are part of frames sent before initalization of the converter (#374)
- General: fix crash that happens during override of publisher
- General: code rewritten to use Golang contexts