Merge "Database: Support parenthesized JOINs"

diff --combined RELEASE-NOTES-1.31
index 5d2d9d9,7597e13..19c135c
--- 1/RELEASE-NOTES-1.31
--- 2/RELEASE-NOTES-1.31
+++ b/RELEASE-NOTES-1.31
@@@ -11,7 -11,8 +11,8 @@@ production
    essential.
  
  === New features in 1.31 ===
- * …
+ * Wikimedia\Rdbms\IDatabase->select() and similar methods now support
+   joins with parentheses for grouping.
  
  === External library changes in 1.31 ===
  
@@@ -45,10 -46,7 +46,10 @@@ changes to languages because of Phabric
  * The global function wfBCP47 was renamed to LanguageCode::bcp47.
  * The global function wfBCP47 is now deprecated.
  * The global function wfCountDown() is now deprecated in favor of
 -  Maintenance::countDown().
 +  Maintenance::countDown()
 +* The OutputPage class constructor now requires a context parameter,
 +  (instantiating without context was deprecated in 1.18)
 +* mw.page (deprecated in 1.30) was removed.
  
  == Compatibility ==
  MediaWiki 1.31 requires PHP 5.5.9 or later. There is experimental support for