Fixes#1103
gortsplib/v2 supports multiple formats inside a single track (media). This allows to apply the resizing algorithm to single formats inside medias.
For instance, if a media contains a a proprietary format and an H264 format, and the latter has oversized packets, they can now be resized.
* API: number of bytes received/sent from/to RTSP connections
* API: number of bytes received/sent from/to RTSP sessions
* API: number of bytes received/sent from/to RTMP connections
* API: number of bytes sent to HLS connections
* API: number of bytes received from paths
* metrics of all the above
* split data into specialized structs
* move MPEG4-audio decoding into streamTrack
* restore video/audio synchronization in HLS muxer and RTMP server
* log decode errors
* move H264 decoding and re-encoding here from gortsplib
* add tests
* update gortsplib
* hls source: support fMP4s video streams
* hls source: start reading live streams from (end of playlist - starting point)
* hls client: wait processing of current fMP4 segment before downloading another one
* hls client: support fmp4 trun boxes with default sample duration, flags and size
* hls client: merge fmp4 init file reader and writer
* hls client: merge fmp4 part reader and writer
* hls client: improve precision of go <-> mp4 time conversion
* hls client: fix esds generation in go-mp4
* hls client: support audio in separate playlist
* hls client: support an arbitrary number of tracks in fmp4 init files
* hls client: support EXT-X-BYTERANGE
* hls client: support fmp4 segments with multiple parts at once
* hls client: support an arbitrary number of mpeg-ts tracks
* hls client: synchronize tracks around a primary track
* update go-mp4
* hls: synchronize track reproduction around a leading one
* hls client: reset stream if playback is too late
* hls client: add limit on DTS-RTC difference
* hls client: support again streams that don't provide codecs in master playlist
