DBus

TODO for DBus integration:

- List all signals, and especially methods that need to be implemented, and list their arguments and return value

- Decide what to do when org.videolan service is already registered by another instance of vlc: let the first instance do all the work ? replace it ? place vlc on the queue ?

- Could vlc be a on-demand startable service, would it be useful ?

Missing features:

volume control => VolumeGet and VolumeSet playlist => hard.... could we use xspf ? timing of the input element (position, jump) preferences ?