macosx/framework: Implement write KVC for VLCMediaList.

Sources/VLCMediaList.m

@@ -187,7 +187,7 @@ static void HandleMediaListItemDeleted( const libvlc_event_t * event, void * use
     return [self count];
 }
 
-- (id)objectInMediaAtIndex:(NSInteger)i
+- (id)objectInMediaAtIndex:(NSUInteger)i
 {
     return [self mediaAtIndex:i];
 }
@@ -197,6 +197,16 @@ static void HandleMediaListItemDeleted( const libvlc_event_t * event, void * use
     return [cachedMedia count];
 }
 
+- (void)insertObject:(id)object inMediaAtIndex:(NSUInteger)i
+{
+    [self insertMedia:object atIndex:i];
+}
+
+- (void)removeObjectFromMediaAtIndex:(NSUInteger)i
+{
+    [self removeMediaAtIndex:i];
+}
+
 @synthesize delegate;
 
 - (BOOL)isReadOnly