ISIS-1414: introduced sequence for chg.xsd so that PublishedObjects can have a sequence; promoted WithTransactionScope interface to applib; QueryResultsCache now implements this interface. The "transactionId" is really an interaction id, and there could be multiple transactions within a single such interaction. Therefore any PublishedObjects (= set of dirtied objects within a transaction) needs to have a sequence number to distinguish from other transactions, and also from any interaction executions.