[Fix] xbmcvfs.exists to support check dir existence. fix #13789
Merge pull request #2528 from ulion/fix_vfs_exists_for_dir_13789

[Fix] xbmcvfs.exists to support check dir existence. fix #13789
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
move NUM_BUFFERS up to BaseRenderer.h
OverlayRenderer: align buffers with index in renderManager
add buffering - submit absolute time to render buffers
RenderManager: some rework to buffering
dvdplayer: disable buffering unil dropping is improved
RenderManager: skip very late frames in render buffer
renderbuffers: drop enable/disable in this iteration
RenderManager: add method SetSpeed
RenderManager: return bufferlevel with WaitForBuffer
OMXPlayer: adapt to buffering