* in Player pipeline, tuned to ensure cached data source not open multiple times on url redirect
* fixed parsing some vtt transcript timing
* extracted speaker in vtt and srt transcripts
* added plain text transcript parser
* show-transcript icon is moved to the top bar of PlayerDetailed and EpisodeInfo
* the caption icon in PlayerDetailed can be long-clicked to set current player position as transcript start
* amended and tidied up transcript popup
