Plugin interface for media player features.

 It provides all of the necessary media player operations,
 and optionally provides the GUI to control them.
 .
 There are two servicetypes for Player:
 KMediaPlayer/Player and KMediaPlayer/Engine.
 KMediaPlayer/Player provides a widget (accessible
 through view as well as XML GUI KActions.
 KMediaPlayer/Engine omits the user interface facets,
 for those who wish to provide their own interface.