Merge "Improve beginMasterChanges and make methods for DeferredUpdates"

diff --cc includes/db/DBConnRef.php
Simple merge

diff --cc includes/db/Database.php
Simple merge

diff --cc includes/db/IDatabase.php
Simple merge

diff --cc includes/db/loadbalancer/LBFactory.php
Simple merge

diff --cc includes/db/loadbalancer/LBFactoryMulti.php
Simple merge

diff --cc includes/db/loadbalancer/LBFactorySimple.php
Simple merge

diff --cc includes/db/loadbalancer/LoadBalancer.php
Simple merge