README.linux update
README.ubuntu update
[pvr] invalidate all items if window becomes invalid
[pvr] fix ctor args for CGUIMessage to re-broadcast observer notify messages
Merge pull request #5038 from xhaggi/pvr-invalid-window-on-channel-switch

[pvr] invalidate window if using fast channel switch
Merge pull request #5011 from uNiversaI/readme

Readme updates
[addons] fix null ptr dereference in GetTranslatedString
videoplayer: adapt lateness detection and dropping to buffering
video player: present correct pts to user for a/v sync (after buffering in renderer)
videoplayer: some rework and documentation
renderer: bump buffers to 5
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
OMXPlayer: some caching fixes for pvr
fix incorrect display of fps when dr kicks in