Fix CurlFile::Exists/Stat for check ftp directory with proper cwd method.
Fix double append to m_curlAliasList bug by NULL check.
Fix memory leak, Exists/Stat allocated resource not released correctly.
Make sure call CurlFile::Exists with url path ends with slash for ftp dir.
Merge pull request #2279 from ulion/fix_curl_slist

Fix curl slist related double append and memory leak
Merge pull request #2274 from ulion/fix_curl_exists_stat_for_ftpdir

Fix CurlFile::Exists/Stat for check ftp directory with proper cwd method.
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
videoplayer: adopt lateness detection and dropping to buffering
video player: present correct pts to user for a/v sync (after buffering in renderer)
vaapi: adopt to buffering in renderer
videoplayer: some rework and documentation
add buffering - some documentation
RenderManager: only flip free buffer if player has added something
OMXPlayer: adopt to buffering
OMXPlayer: enable buffering