Update license boilerplate

COPYRIGHT

@@ -2,11 +2,11 @@
 libimagequant is derived from code by Jef Poskanzer and Greg Roelofs
 licensed under pngquant's original license (at the end of this file),
 and contains extensive changes and additions by Kornel Lesiński
-licensed under GPL v3.
+licensed under GPL v3 or later.
 
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-libimagequant © 2009-2016 by Kornel Lesiński.
+libimagequant © 2009-2017 by Kornel Lesiński.
 
                     GNU GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007

example.c

@@ -21,6 +21,8 @@ On "manually":
    gcc -O3 example.c libimagequant.a -o example
    ./example truecolor_file.png
 
+
+This example code can be freely copied under CC0 (public domain) license.
 */
 
 #include "lodepng.h" // Get it from https://raw.githubusercontent.com/lvandeve/lodepng/master/lodepng.h

kmeans.c

@@ -1,20 +1,6 @@
 /*
-© 2011-2016 by Kornel Lesiński.
-
-This file is part of libimagequant.
-
-libimagequant 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.
-
-libimagequant 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 libimagequant. If not, see <http://www.gnu.org/licenses/>.
+** © 2011-2016 by Kornel Lesiński.
+** See COPYRIGHT file for license.
 */
 
 #include "libimagequant.h"

libimagequant.c

@@ -1,31 +1,9 @@
 /*
-** © 2009-2016 by Kornel Lesiński.
+** © 2009-2017 by Kornel Lesiński.
+** © 1989, 1991 by Jef Poskanzer.
+** © 1997, 2000, 2002 by Greg Roelofs; based on an idea by Stefan Schneider.
 **
-** This file is part of libimagequant.
-**
-** libimagequant 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.
-**
-** libimagequant 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 libimagequant. If not, see <http://www.gnu.org/licenses/>.
-*/
-/* Copyright (C) 1989, 1991 by Jef Poskanzer.
-** Copyright (C) 1997, 2000, 2002 by Greg Roelofs; based on an idea by
-**                                Stefan Schneider.
-**
-** Permission to use, copy, modify, and distribute this software and its
-** documentation for any purpose and without fee is hereby granted, provided
-** that the above copyright notice appear in all copies and that both that
-** copyright notice and this permission notice appear in supporting
-** documentation.  This software is provided "as is" without express or
-** implied warranty.
+** See COPYRIGHT file for license.
 */
 
 #include <stdio.h>

libimagequant.cs

@@ -1,3 +1,9 @@
+/*
+This is an example demonstrating use of libimagequant from C#.
+
+This example code can be freely copied under CC0 (public domain) license.
+*/
+
 using System;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;

mediancut.c

@@ -1,32 +1,9 @@
 /*
-** © 2009-2015 by Kornel Lesiński.
+** © 2009-2017 by Kornel Lesiński.
+** © 1989, 1991 by Jef Poskanzer.
+** © 1997, 2000, 2002 by Greg Roelofs; based on an idea by Stefan Schneider.
 **
-** This file is part of libimagequant.
-**
-** libimagequant 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.
-**
-** libimagequant 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 libimagequant. If not, see <http://www.gnu.org/licenses/>.
-*/
-/*
-** Copyright (C) 1989, 1991 by Jef Poskanzer.
-** Copyright (C) 1997, 2000, 2002 by Greg Roelofs; based on an idea by
-**                                Stefan Schneider.
-**
-** Permission to use, copy, modify, and distribute this software and its
-** documentation for any purpose and without fee is hereby granted, provided
-** that the above copyright notice appear in all copies and that both that
-** copyright notice and this permission notice appear in supporting
-** documentation.  This software is provided "as is" without express or
-** implied warranty.
+** See COPYRIGHT file for license.
 */
 
 #include <stdlib.h>

mempool.c

@@ -1,20 +1,9 @@
 /*
-© 2011-2016 by Kornel Lesiński.
-
-This file is part of libimagequant.
-
-libimagequant 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.
-
-libimagequant 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 libimagequant. If not, see <http://www.gnu.org/licenses/>.
+** © 2009-2017 by Kornel Lesiński.
+** © 1989, 1991 by Jef Poskanzer.
+** © 1997, 2000, 2002 by Greg Roelofs; based on an idea by Stefan Schneider.
+**
+** See COPYRIGHT file for license.
 */
 
 #include "libimagequant.h"

nearest.c

@@ -1,20 +1,9 @@
 /*
-© 2011-2015 by Kornel Lesiński.
-
-This file is part of libimagequant.
-
-libimagequant 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.
-
-libimagequant 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 libimagequant. If not, see <http://www.gnu.org/licenses/>.
+** © 2009-2015 by Kornel Lesiński.
+** © 1989, 1991 by Jef Poskanzer.
+** © 1997, 2000, 2002 by Greg Roelofs; based on an idea by Stefan Schneider.
+**
+** See COPYRIGHT file for license.
 */
 
 #include "libimagequant.h"

pam.c

@@ -1,16 +1,10 @@
 /* pam.c - pam (portable alpha map) utility library
 **
-** Copyright (C) 1989, 1991 by Jef Poskanzer.
-** Copyright (C) 1997, 2000, 2002 by Greg Roelofs; based on an idea by
-**                                Stefan Schneider.
-** © 2009-2016 by Kornel Lesinski.
+** © 2009-2017 by Kornel Lesiński.
+** © 1989, 1991 by Jef Poskanzer.
+** © 1997, 2000, 2002 by Greg Roelofs; based on an idea by Stefan Schneider.
 **
-** Permission to use, copy, modify, and distribute this software and its
-** documentation for any purpose and without fee is hereby granted, provided
-** that the above copyright notice appear in all copies and that both that
-** copyright notice and this permission notice appear in supporting
-** documentation.  This software is provided "as is" without express or
-** implied warranty.
+** See COPYRIGHT file for license.
 */
 
 #include <stdlib.h>