* In MagicWord::initRegex(), put the longest synonyms first in the alternation. This means that when one synonym is an initial substring of another, the longest one will match in precedence, which is generally in line with user expectations.
* In MagicWordArray::matchStartAndRemove(), fixed the case where the length of localised synonym is not precisely the length of the magic word ID plus one
* Fixed the case where matchStartAndRemove() removes the entire string, send empty string not false
* Fix brace style
* The serialized message cache, which would have been redundant, has been removed. Similar performance characteristics can be achieved with $wgLocalisationCacheConf['manualRecache'] = true;
* Added a maintenance script rebuildLocalisationCache.php for offline rebuilding of the localisation cache.
* Extension i18n files can now contain any of the variables which can be set in Messages*.php. It is possible, and recommended, to use this feature instead of the hooks for special page aliases and magic words.
* $wgExtensionAliasesFiles, LanguageGetMagic and LanguageGetSpecialPageAliases are retained for backwards compatibility. $wgMessageCache->addMessages() and related functions have been removed. wfLoadExtensionMessages() is a no-op and can continue to be called for b/c.
* Introduced $wgCacheDirectory as a default location for the various local caches that have accumulated. Suggested $IP/cache as a good place for it in the default LocalSettings.php and created this directory with a deny-all .htaccess.
* Patched Exception.php to avoid using the message cache when an exception is thrown from within LocalisationCache, since this tends to fail horribly.
* Removed Language::getLocalisationArray(), Language::loadLocalisation(), Language::load()
* Fixed FileDependency::__sleep()
* In Cdb.php, fixed newlines in debug messages
In MessageCache::get():
* Replaced calls to $wgContLang capitalisation functions with plain PHP functions, reducing the typical case from 99us to 93us. Message cache keys are already documented as being restricted to ASCII.
* Implemented a more efficient way to filter out bogus language codes, reducing the "foo/en" case from 430us to 101us
* Optimised wfRunHooks() in the typical do-nothing case, from ~30us to ~3us. This reduced MessageCache::get() typical case time from 93us to 38us.
* Removed hook MessageNotInMwNs to save an extra 3us per cache hit. Reimplemented the only user (LocalisationUpdate) using the new hook LocalisationCacheRecache.
Side effect: Removed "Pages in namespace (Magic word disabled currently)" parser test added in r17687 by nickj (was passing; I know). The problem is that the expected result is an empty string, but since it's disabled by default with $wgAllowSlowParserFunctions = false (i.e. not added to parser's list of magic words IDs) it should return a red link to [[Template:PAGESINNAMESPACE:]] (the empty string is produced because "{{PAGESINNAMESPACE:}}" is handled as variable and not as parser function).
* Currently __INDEX__ will override __NOINDEX__ regardless of their relative positions, due to the way things are written. Instead, the last one on the page should win. This should be pretty easy to fix.
* __INDEX__ and __NOINDEX__ override $wgArticleRobotPolicies. This is almost certainly incorrect, but it's not totally obvious how to fix it, because of the way the code is structured. Probably not a big deal, but should probably be fixed at some point.
* Anyone can add and remove the magic words, and there's no config option to disable them. It's not obvious whether this is okay or not. It would be a one-line change to OutputPage.php to have a config option to ignore the magic words, maybe per-namespace or who knows what.