* Add @addtogroup tags to various classes, to try and group conceptually-related classes together.
* Add brief descriptions to various Special pages, thanks to Phil Boswell.
* Moving some docs to be right above the classes they represent, so that they are picked up.
* removing some unused global declarations.
* removing or commenting out or adding comments for unused local vars.
* Adding one or two local var declarations.
* Declaring $matches array passed to preg_match() / preg_match_all() as array() before using [not required, just have a slight preference for the explicitness].
* remove one or two pass-by-reference function declarations where the value is not modified.
* Adding some braces to if-else blocks.
* In Parser.php, stripstrate is now an object rather than an array as per r17820, so we no longer need ask for a reference to it (as in "$x =& $this->mStripState;"), and in fact it's probably just simpler to get rid of $x altogether.
* Moving some preg regexes from "" quoting to '' quoting to stop static analyzer whinging about bad escape sequences.
... up to "LinksUpdate.php" in the includes/ directory.
* API: added experimental watchlist rss/atom feed
* API: if available, json_encode() will be used
* API: opensearch parameter changed to "search=" (more descriptive)
* API: minor parameter cleanup, a wrapper for Feed class
