This simplifies the code a little, and removes the need for the
stream_CommonDelete() hack due to inverted stream/access parentage.

Attach to the source stream´s parent rather than the source stream.
This avoids recursive vlc_object_release() when deleting the chain.

background style was never applied when set to non text mode.

background is always rendered on region depending on renderer

This avoids leaking disk space if VLC does not terminate cleanly.

The vlc_stat() call did not really ensure that the directory was usable
(space and permission), nor that it would still exist when needed.

Now instead, try to create the temporary file and fall back to the
default path if that fails.