Reusing settings from before 1.1.0 results in a mess.

We don't use GLX with Xomap (rather XV or X11)

In 0.9, the output refuses to work and the codec just segfaults.
In 1.0, it is inoperant due to the removal of the forked libmpeg2.
In 1.1, we would anyway need to rewrite it to the new vout API.

GLX does not use SysV shared memory directly.

This smells like fishy cut&paste from the former XV plugin.

Keeps previous behavior when subtitles overlapped in time,
except when trying to move subtitles below the bottom picture edge
-> they start to visually overlap because of bounding.

This reverts commit 4c627dc6.

Fixes the glitch when displaying subtitles and subtitle position != 0.
Modifies behavior when subtitles overlap: newer subtitles push older ones higher

The file associations need to be implemented

The execution of a seek command will be postpone until the decoder has finished
its bufferisation (or until 125ms has elapsed since the last seek).

If the access does not support CAM, we need to free the PMT
(closes #3163)

+ remove a dead line & kill a warning