* 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.
* @link. You might think @link would surely mean "here comes a web URL" ... but @link is a valid command
in Doxygen, which means an entirely different kind of link (an internal link to somewhere, so that you can separate
documentation and implementation). The result is a mess, and the best solution I can see is to use "@see" instead of "@link".
* Warning: argument `nourl' of command @param is not found in the argument list of Linker::makeMediaLinkObj($title,$text='')
* Moving few class descriptions to right above classes, and/or formatting into Javadoc style.
* "@addtogroup Special Pages" --> "@addtogroup SpecialPage" so that all special pages have the same @addtogroup tag.
* @fixme --> @todo (must have missed these before)
* "@param $specialPage @see" remove the "@" in the "@see" to stop warning.
* @throws wants type, then a brief description, to stop warning.
This last one is for PHPdocumentor only, but it fixes something for PHPDocumentor, and should be neutral for Doxygen:
* WARNING in includes/api/ApiFormatYaml_spyc.php on line 860: docblock template never terminated with /**#@-*/
