DibiConnection: inTransaction() is back, implemented in drivers

dibi/libs/interfaces.php

@@ -145,6 +145,12 @@ interface IDibiDriver
 	 */
 	function rollback($savepoint = NULL);
 
+	/**
+	 * Is in transaction?
+	 * @return bool
+	 */
+	function inTransaction();
+
 	/**
 	 * Returns the connection resource.
 	 * @return mixed