Move list retrieve/render to class (#15)

- array_key_exists -> key_exists

src/public/user/log-off.php

@@ -5,6 +5,6 @@
 
 include '../../start.php';
 
-if (array_key_exists(Key::USER_ID, $_SESSION)) session_destroy();
+if (key_exists(Key::USER_ID, $_SESSION)) session_destroy();
 
 frc_redirect('/');

src/public/user/log-on.php

@@ -5,7 +5,7 @@ $db = Data::getConnection();
 Security::verifyUser($db, redirectIfAnonymous: false);
 
 // Users already logged on have no need of this page
-if (array_key_exists(Key::USER_ID, $_SESSION)) frc_redirect('/');
+if (key_exists(Key::USER_ID, $_SESSION)) frc_redirect('/');
 
 if ($_SERVER['REQUEST_METHOD'] == 'POST') {
     Security::logOnUser($_POST['email'] ?? '', $_POST['password'], $_POST['returnTo'] ?? null, $db);