PHP/Core

* enforced v7.1 compliance, preparations for v7.2
 * removed deprecated usage of each()
 * prefer array deconstruction via [] instead of calling list()
 * try to catch failed session_start()
 * prefer ... - Token instead of calling func_get_args() func_num_args()
 * enforce return types in AjaxHandler
 * revision push

index.php

@@ -90,8 +90,10 @@ switch ($pageCall)
         $cleanName = str_replace(['-', '_'], '', ucFirst($altClass ?: $pageCall));
         try                                                 // can it be handled as ajax?
         {
+            $out   = '';
             $class = 'Ajax'.$cleanName;
             $ajax  = new $class(explode('.', $pageParam));
+
             if ($ajax->handle($out))
             {
                 Util::sendNoCacheHeader();