[pvr] fix deviations of selected item between PVR windows and channel OSD

As discussed in our forum (http://forum.xbmc.org/showthread.php?tid=175135&pid=1795411#pid1795411) this fix the deviations of the selected item between the PVR windows and the channel osd.

I also changed the way the current playing channel is used for the selected item. It's only used if we never have valid selected item or if we switch the channel otherwise we use the stored selected item. Thanks Jönke for this suggestion.
[pvr] cosmetics: correct wrong code format
[pvr] fix backend info never gets updated when only one pvr client enabled
[pvr] add ability to show free/used disk space of backend
Merge pull request #5401 from xhaggi/pvr-fix-sync-selected-item

[pvr] fix deviations of selected item between PVR windows and channel OSD
[confluence] add pvr disk indicator in recordings view
Merge pull request #5303 from Glenn-1990/pvr_diskspace

[pvr] diskspace indicator in recordings view
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