[Umbrella] ASCollectionView -> ASCollectionNode Migration, Separate Index Spaces (#2372)

* Separate dataSource & UIKit index spaces

Beef up our supplementary node support

Make the API way better

Go nuts

Add a unit test for UICollectionView's handling of reloadData inside batch updates

Wrap indexPathForNode: in a cache

Convert index paths in delegate methods

Go back on table view

Put collection view back

Switch up the API

Move most ASCollectionView API to ASCollectionNode

Move most table logic over to ASTableNode

Do the things

More conversion work

Keep on keepin' on

Get table view delegate API done

More porting

Simplify

Clear the delegate

More cleanup

Move more stuff around

Remove pointless file

Re-add some API

Put back more API

Use the right flag

* Some cleanup

* Remove incorrect comment

* Tweak the API

* Put back a couple methods

* update example projects (note: ASCollectionView deprecation warnings expected)

* change reloadDataWithCompletion:nil --> reloadData

* Clean up rebase

* Make deprecated numberOfItemsInSection methods optional

* Use the right flag

* Address nits

* update ASDKTube, ASDKgram & ASViewController examples

examples/CustomCollectionView/Sample/MosaicCollectionViewLayout.m

@@ -214,18 +214,6 @@
   return ASSizeRangeMake(CGSizeZero, [layout _headerSizeForSection:indexPath.section]);
 }
 
-/**
- * Asks the inspector for the number of supplementary sections in the collection view for the given kind.
- */
-- (NSUInteger)collectionView:(ASCollectionView *)collectionView numberOfSectionsForSupplementaryNodeOfKind:(NSString *)kind
-{
-  if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
-    return [[collectionView asyncDataSource] numberOfSectionsInCollectionView:collectionView];
-  } else {
-    return 0;
-  }
-}
-
 /**
  * Asks the inspector for the number of supplementary views for the given kind in the specified section.
  */
@@ -238,4 +226,4 @@
   }
 }
 
-@end
+@end