Plugin with Fatal error

Your class_exists(WikiLinksPlugin) call is calling WikiLinksPlugin as a constant, rather than as a value passed to class_exists().

It should be this (quotes around the class name):

if (class_exists( "WikiLinksPlugin" ) && !isset($wikiLinks_plugin)) {
    $wikiLinks_plugin = new WikiLinksPlugin();    
}

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)