[pvr] fix internal group loading

As we never load the internal groups from our TV database, changing the group name in our group manager has no effect. This fixes the loading of the internal channel groups.
[pvr] cosmetics: refactor internal group id constants to be more meaningful
Merge pull request #5376 from xhaggi/pvr-fix-internal-group-loading

[pvr] fix internal group loading
videoplayer: adapt lateness detection and dropping to buffering
video player: present correct pts to user for a/v sync (after buffering in renderer)
videoplayer: update frametime, it might change due to fps detection
videoplayer: give streams with invalid fps a chance for fps detection
dvdplayer: allow rewinding at end of stream, do a seek after rewind
dvdplayer: observe pts counter overflow
dvdplayer: avoid short screen flicker caused by unnecessary reconfigure of renderer
vdpau: advanced settings for auto deinterlacing
player: fix rewind
fix incorrect display of fps when dr kicks in
ActiveAE: slightly reduce buffer size
Revert "vdpau: comment some features that will be added later"

This reverts commit e00b4f65864d623ab4d2e9e5c06db138e661f1cf.
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
xbmc pr 3080