Magical Record without parent contexts

MagicalRecordNoParents.m

//Also fine to use MR_coordinatorWithInMemoryStore
NSPersistentStoreCoordinator *coordinator = [NSPersistentStoreCoordinator MR_newPersistentStoreCoordinator];
[NSPersistentStoreCoordinator MR_setDefaultStoreCoordinator:coordinator];
NSManagedObjectContext *defaultContext = [NSManagedObjectContext MR_newMainQueueContext];
defaultContext.persistentStoreCoordinator = coordinator;
[NSManagedObjectContext performSelector:@selector(MR_setDefaultContext:) withObject:defaultContext];