avio_flush can fail, in particular when used with the rtmp/librtmp
protocol.

It's simpler and less error-prone.

Fixes some memleaks along the way.

This fixes 'make checkheaders'.

Most of these variables are only used in av_dlog statements, some
are required but not used by other macros.
Signed-off-by: NMans Rullgard <mans@mansr.com>

The 'edts' write function can now generate an initial empty edit resulting in a track-specific presentation delay.
This is automatically calculated and inserted for any track where the initial DTS != 0.
Added support for long (version==1) timecodes.

Create a stereo_mode metadata tag to specify the stereo 3d video layout
using the StereoMode tag in a matroska/webm video track.

Instead of -fflags rtphint, set -movflags rtphint instead.
Signed-off-by: NMartin Storsjö <martin@martin.st>

Signed-off-by: NMartin Storsjö <martin@martin.st>

The connect() timeout can take minutes, gets misreported as EIO and
isn't interruptible.

Deprecate corresponding AVFormatParameters field.