- removed the defines for i_mode concerning random and loop. We use config
    variables for all of these.
* src/libvlc.h:
  - removed the enqueue playlist config option. It's no longer used.
  - added a repeat option. vlc will keep playing the same playlist_item,
    until the option is unset.
* src/playlist/playlist.c:
  - added a repeat, random and loop variable.
  - wxwindows should use these as well I think.
* modules/gui/macosx:
  - added the INTF_ABOUT_MSG to the about dialog.
  - implemented the about and repeat items.