Ref #3804

This rework includes:
   - activation with mouse move
   - transparency and fading out supported if the WM allows it
   - fsc no longer a child window
     (this latter point should work out the refresh problems
      often mentioned on Vista and Win7)

The possibility to trigger callbacks when changing preferences was removed
 lately. So this code is now useless.

It cannot work properly due to SIGBUS when a file gets truncated.
In fact, this plugin had been disabled by default for as long as it had
been in VLC.

Based on keep-alive RTSP requests

CommonDisplay() must be called at least once to ensure that the window
content is shown.

It computes correct crop/ar settings when scaling a video format.

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

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

Move logging of current segment and stream. The previous place gave
confusing information.

After the adaptive bandwidth changes seeking could end up in a segment
that is not available. Each segment is downloaded once and after switching
to higher or lower bandwidth segments downloaded for previous bandwidths
will not be deleted or downloaded. The later is to be fixed.

Start playback with the lowest bandwidth stream.

NextSegment() assumed that the download thread its hls_stream_t was leading.
However this was too simplistic.

NextSegment() seeks the segment in *any* of the hls_stream_t, assuming that
each segment will be downloaded only once.

Test script for traffic shaping with tc (iproute).

Download the next segment from a playback standpoint.

Cleanup NextSegment().

The bandwidth calculation needed corrections and is less agressive in
switching to higher bandwidths.

(It was broken by a8e4b30b)

Move the definition to qt4.hpp and add a comment

If you want to use #description, you need to set up the appropriate
struct on pass it down as a variable

This also fixes error handling: if the thread cannot be created, we do
fail cleanly.