ffmpeg demuxer: faster channel change for PVR addons without internal demuxing
(such as MediaPortal, ArgusTV, MythTV, NextPVR)
Credits: FernetMenta, Davilla, Popcornmix, Whaupt
DVDFactoryDemuxer: skip streaminfo for udp tcp and pvr-channels
fast channel switch, make sure extradata is decoded
ffmpeg demuxer: allow a stream change if pat/pmt was not seen on open
fastswitch: do not reduce time to analyze when looking for metadata
Merge pull request #5487 from FernetMenta/fastswitch

dvdplayer: faster channel switching and playback for mpegts