+* PrefixSearchBackend hook now has an $offset parameter. Combined with $limit,
+ this allows for pagination of prefix results. Extensions using this hook
+ should implement supporting behavior. Not doing so can result in undefined
+ behavior from API clients trying to continue through prefix results.
+
+==== External libraries ====
+* MediaWiki now requires certain external libraries to be installed. In the past
+ these were bundled inside the Git repository of MediaWiki core, but now they
+ need to be installed separately. For users using the tarball, this will be taken
+ care of and no action will be required. Users using Git will either need to use
+ composer to fetch dependencies or use the mediawiki/vendor repository which includes
+ all dependencies for MediaWiki core and ones used in Wikimedia deployment. Detailed
+ instructions can be found at:
+ https://www.mediawiki.org/wiki/Download_from_Git#Fetch_external_libraries
+* The following libraries are now required:
+** psr/log
+ This library provides the interfaces set by the PSR-3 standard (http://www.php-fig.org/psr/psr-3/)
+ which are used by MediaWiki interally by the MWLogger class.
+ See the structured logging RfC (https://www.mediawiki.org/wiki/Requests_for_comment/Structured_logging)
+ for more background information.
+** cssjanus/cssjanus
+ This library was formerly bundled with MediaWiki core and has been removed.
+ It automatically flips CSS for RTL support.
+** leafo/lessphp
+ This library was formerly bundled with MediaWiki core and has been removed.
+ It compiles LESS files into CSS.
+** wikimedia/cdb
+ This library was formerly a part of MediaWiki core, and has been moved into a separate library.
+ It provides CDB functions which are used in the Interwiki and Localization caches.
+ More information about the library can be found at https://www.mediawiki.org/wiki/CDB.