Add "wikitext" as a language lexer in Pygments, as used in Extension:SyntaxHighlight
See attachment below for (incomplete) lang='mediawiki" patch.
Upstream Pygments feature request: https://github.com/pygments/pygments/issues/827
Older notes at the GeSHi feature requests: http://sourceforge.net/p/geshi/feature-requests/112/ ("wikitext") and https://sourceforge.net/p/geshi/feature-requests/84/ (MediaWiki). (but nothing in GeSHi's newer GitHub issues).