MacOSX/Framework: No more rely on media_descriptor_(get/set)_user_data, now that we cache the media decriptor. (We may want to revert that back one day, but right now this doesn't work, and trigger some strange bugs here).

MacOSX/Framework/VLCMediaListAspect.m: Use a NSMutableArray to cache the media list view items. (for the same reason given in previous commit).

MacOSX/Framework/VLCMediaList.m: Cache the media list objects in a NSMutableArray. We do this because we want to use bindings. Cocoa bindings requires us to send willChangeValueForKey/didChangeValueForKey on the main thread. And that's one of the simpler way to do that without having locking problems.

heavy simplification, and fix(/remove) piles of error cases.
Server gets to choose the charset anyway.

MacOSX/Framework/VLCMediaList.m: Don't forget to alloc an autorelease pool on function that may be called from a non-main thread context.

MacOSX/Framework: Use mediaListWithLibVLCMediaList instead of media*l*istWithLibVLCMediaList, to match the VLCMediaList class name cases.

Also the soundSlider takes it first value from the preferences...

Need a lot of graphic tweaking.

Slovenian translation updates by Matej Urbančič