Update of topical areas on master should be reflected in instances

[douglm]

• create recurring event
• check instances' topical area
• change topical area in master 0 instances should change also
• change description in one instance to create an override
• change topical area in instance - should have no effect (should probably warn rather than ignore)
• chnage topical area in master - will be reflected in non-overridden instances - but not in override.