Work done by NightStrike

and the pointer is never modified).

This reverts "test: Disable test_media_list_player as it deadlocks."

This reverts commit 3403c427.

Also fix the initial refcount for the media list, that was causing a bunch of problem on the test suite.

vlc_assert_locked should probably be exported, as it would have been useful here.

so eg mobile-stream goes like this
--sout="#transcode{vcodec=h264,venc=x264{profile=baseline,level=12},...."

..or it magically eats itself up

...and fix memleak when removing..

If playlist view was full with items it was hard/impossible to
add node to root if the action operated on right-clicked item.
Sort action follows the same style for consistence and practicality.