VideoRenerers: add buffering
add buffering for GLES
WinRenderer: add buffering
DXVA: activate buffering in renderer
linuxrenderer: delete all textures on reconfigure
drop frame counter in application, ask render manager instead
vaapi: adopt to buffering in renderer
add buffering - some documentation
RenderManager: only flip free buffer if player has added something
move NUM_BUFFERS up to BaseRenderer.h
OverlayRenderer: align buffers with index in renderManager
add buffering - submit absolute time to render buffers
OMXPlayer: adapt to buffering
RenderManager: some rework, squash add buffering
dvdplayer: disable buffering unit dropping is improves
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
Revert "dvdplayer: disable buffering unit dropping is improves"

This reverts commit de1caf5686c1fb53cb7ab11b356e6c22770740db.
configure: add --enable-pvraddons-with-dependencies switch
for intree building of PVR Addons