Add source headers to setup and start files, and keep windows start file

setup.py

@@ -1,12 +1,28 @@
 #!/usr/bin/env python3
+# -*- coding: utf-8 -*-
 """
-The main setup script for novelWriter.
+novelWriter – Main Setup Script
+===============================
+The main setup and install script for all operating systems
 
-It runs the standard setuptool.setup() with all options taken from the
-setup.cfg file.
+File History:
+Created: 2019-05-16 [0.5.1]
 
-In addition, a few specialised commands are available. These are
-described in the help text in the main section.
+This file is a part of novelWriter
+Copyright 2018–2021, Veronica Berglyd Olsen
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU 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
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <https://www.gnu.org/licenses/>.
 """
 
 import os