Playlist now supports dragging tracks out of app

Playlist now supports dragging copies of URL references to other apps,
including Finder, and possibly other audio players. The chosen drag
operation is to copy files.

Fixes #75

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Playlist/PlaylistController.m

@@ -117,6 +117,8 @@ static NSArray *cellIdentifiers = nil;
 	          options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld)
 	          context:nil];
 	[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.fontSize" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionInitial) context:nil];
+
+	[self.tableView setDraggingSourceOperationMask:NSDragOperationCopy forLocal:NO];
 }
 
 - (void)observeValueForKeyPath:(NSString *)keyPath