Use http instead of https in gvctrl getLogin request. Gave RTP client a close method so that the conn can
be closed after we're done with the client. Put timeout on reading from the RTP client PacketConn so that
we don't hang on the ReadFrom call if the conn is closed. Closing the RTSP and RTP clients when
startRTSPCamera is returned.
Two fixes were involved, firstly, access unit delimeters were used to denote access units and the Write timeout on rtmpSender's ringBuffer was
increased to stop the 'unable to dump old write' errors. Also made some small changes elsewhere that should fix future issues, particular with
MTS output.
Renamed the RTPLexer to Extracter, renamed NewRTPLexer to NewExtracter and renamed Lex to Extract. Put Extracter and accompanying methods in file extract.go.
Put tests relating to Extracter in extract_test.go.