syntax.php: Search pattern corrections

++ What: (1) replacing "addEntryPattern" (ill formed without corresponding "addExitPattern") by "addSpecialPattern"; (2) replacing RegEx ".*" by "[^>]" ("stop at next >")
++ Why: (1) formal correctness; (2) to use hiddenSwitch before other patterns or literal text that embody ">" (e.g. hidden plugin ...)
++ Note: Compare with Fabrizio's remarks on https://www.dokuwiki.org/plugin:hiddenswitch (2011/12/03 11:30) - which are, nevertheless, not fully correct
    $this->Lexer->addSpecialPattern('<hiddenSwitch[^>]*>', $mode,'plugin_hiddenSwitch');