Model updates

Since SisoDb stores the object graph representation as JSON and as a flattened object in the Indexes-tables using key-values, you could of course update the values in the Indexes-tables using T-SQL and also try to update the JSON member using T-SQL, but sometimes you might want to perform more advances updates, and then you basically do have to re-save the structures, and that's where the Maintenance API can help you.