Detach all pages of the main form

Source/GrasscutterTools/Pages/PageGiveArtifact.cs

@@ -1,4 +1,23 @@
-using System;
+/**
+ *  Grasscutter Tools
+ *  Copyright (C) 2022 jie65535
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ **/
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Windows.Forms;