Make some sttings persistent

Not thorougly tested. Olivier reverts this commit without hesitation if it breaks your stuffs

Put the add button in the playlist standard panel
Remove duplicated code for playlist widgets

Add button in playlist widget

  - It now uses in order
   default fps == 25,
   the fps of the movie, if available.
   the fps specified in the subtitle file, if available.
   the fps specified by the user, if set.
  - Don't set it on each an every subtitle, do it globaly. (should be faster)

  Info was distilled from the mplayer codec config file

  closes #750

mc.get_instance to mc.get_vlc_instance

python bindings: changes from the libvlc API: a MediaControl can now be created from scratch (with a list of strings as parameters) or from an existing vlc.Instance. MediaControl.get_instance() return the associated vlc.Instance in all cases.

- ActiveX: optimized implementation of all IEnumXXX classes (more template obfuscation I'm afraid), fixed IConnectionPoints for DCOM

Cosmetics

bindings (vlm methods)