getDB(), getRootDB()를 autoload 클래스로 변경

- 각각 DB::db(), RootDB::db()임.

i_entrance/entrance.php

@@ -7,7 +7,7 @@ $session = Session::requireLogin();
 
 $templates = new \League\Plates\Engine('templates');
 
-$db = getRootDB();
+$db = RootDB::db();
 $notice = $db->queryFirstField('SELECT `NOTICE` FROM `SYSTEM` WHERE `NO`=1');
 $userGrade = $session->userGrade;
 ?>