* Removes the need to manually enable replicators in order for an applier to work. * Removes the enabled/disabled setting of both transaction applier plugins and transaction replicator plugins * Pairs a replicator with an applier into a "ReplicationStream" and removes all checks for "enabled" replicators and appliers * Allows modules that implement a TransactionApplier (such as the transaction_log module) to specify which replicator to use via a configuration variable. For instance, the transaction log module now has --transaction-log-use-replicator=[default|filtered..] instead of the user having to do --default-replicator-enable and such * Adds a new data dictionary table for REPLICATION_STREAMS, which allows querying of activated replication-to-applier streams managed by drizzled::ReplicationServices