Check whether the "INBOX" folder has the "noinferiors" flag set before declaring that it accepts subfolder creation

OpenChange/MAPIStoreUserContext.h

@@ -58,6 +58,8 @@
 
   WOContext *woContext;
   MAPIStoreAuthenticator *authenticator;
+
+  BOOL inboxHasNoInferiors;
 }
 
 + (id) userContextWithUsername: (NSString *) username
@@ -75,6 +77,8 @@
 
 - (NSDictionary *) rootFolders;
 
+- (BOOL) inboxHasNoInferiors;
+
 - (NSURL *) folderTableURL;
 - (MAPIStoreMapping *) mapping;