Base parent model for playlist

This is useful when building with compilers like clang+llvm which do not
plan on implementing this extension.
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

Sorry for the mistake

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Reported by Pankaj Yadav

Signed-off-by: Rémi Duraffort <ivoire@videolan.org>

Pointed-out-by: 김정은 <sunqueen@paran.com>

This requires a bleeding edge liblive555 - not tested.

Modified by Jean-Baptiste Kempf, to fit option style
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

All members that where previously part of struct hls_thread_s have been
moved to stream_sys_t. The purpose of having this structure and vlc_object_t
is no longer needed.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Signed-off-by: Laurent Aimar <fenrir@videolan.org>

Rename p_sys->download.current and p_sys->playback.current to
p_sys->download.stream and p_sys->playback.stream.

Playback of live streams with HLS started at index 0 from the downloaded playlists. For
live streams it is more natural to be closer to the end of the playlist, but not within
the last 3 segments of the stream.

The playback stalling warning was printed too often. Only print this message when
playback is in real danger and check only on segment boundaries.

Then again, many developers have Christian first names (most noticeably
"Christophe").

This should be installed locally as it can't be crosscompiled. Recommendation: Homebrew

Cleanup hls_Thread().

Check only for live streams the member p_sys->playlist.wakeup.

Cleanup hls_thread_t and stream_sys_t structs:
- duplicate members
- rename hls_playlist_t to hls_playlist_s
- move download members to stream_sys_t inside a hls_download_s struct
- check for p_sys->thread is no longer needed in segment_Seek()