[ASDataController] Add validation logic to the change set to throw exceptions on invalid updates (#1894)

[_ASHierarchyChangeSet] Oopsy daisy

[ASDataController] Tweak our update validation

[ASHierarchyChangeSet] Fix bugs

Finish up some stuff

[ASDataController] Put some stuff back

[ASChangeSetDataController] Always use changeset

[ASDataController] Put other stuff back

[_ASHierarchyChangeSet] Use fast enumeration

[_ASHierarchyChangeSet] Fix assertion format strings, return on fail so we don't crash in production

[ASDataController] Store data source item counts as vector rather than NSArray

[ASDataController] Build some tests for the update validation

[ASDataController] Fix issues with update validation

Get rid of new file

[ASDataController] Suppress changeset validation before initial reload

[ASDataController] Make invalid update log vs. exception publicly toggleable

AsyncDisplayKit/Details/ASDataController.h

@@ -124,6 +124,15 @@ FOUNDATION_EXPORT NSString * const ASDataControllerRowNodeKind;
  */
 @property (nonatomic, weak) id<ASDataControllerEnvironmentDelegate> environmentDelegate;
 
+/**
+ * Returns YES if reloadData has been called at least once. Before this point it is
+ * important to ignore/suppress some operations. For example, inserting a section
+ * before the initial data load should have no effect.
+ *
+ * This must be called on the main thread.
+ */
+@property (nonatomic, readonly) BOOL initialReloadDataHasBeenCalled;
+
 /** @name Data Updating */
 
 - (void)beginUpdates;