For some reason, vlc event handlers are not re-entrant (https://github.com/oaubert/python-vlc/issues/44#issuecomment-378520074).
This means that the vlc API can't be used from an event handler,
and that an event handler that reacts to stop/end-of-stream by
releasing the player and the vlc instance will likely get stuck
and the app may eventually die with SIGSEGV.
Because of this design limitation on the vlc side, the plugin has
to run another thread in the main app that monitors the stop event
set by the event handler and releases the resources appropriately.
Fabio Manganiello
833f810d4b