Clarify licenses

- add license headers to everything
- convert a few files from public domain or LGPL2.1+ to GPL2+
- some archaeology to clarify which files are from which library

20 files changed, 40 insertions, 20 deletions

diff --git a/src/extension/param/bool.cpp b/src/extension/param/bool.cpp
index 1ba9f6633..10121f7ab 100644
--- a/src/extension/param/bool.cpp
+++ b/src/extension/param/bool.cpp
@@ -1,9 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/adjustment.h>
diff --git a/src/extension/param/bool.h b/src/extension/param/bool.h
index f987621d5..9864cac38 100644
--- a/src/extension/param/bool.h
+++ b/src/extension/param/bool.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef SEEN_INK_EXTENSION_PARAMBOOL_H
 #define SEEN_INK_EXTENSION_PARAMBOOL_H
 /*
@@ -5,7 +6,7 @@
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/color.cpp b/src/extension/param/color.cpp
index 6ce5d78b1..f71670cb2 100644
--- a/src/extension/param/color.cpp
+++ b/src/extension/param/color.cpp
@@ -1,10 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl>
  *   Christopher Brown <audiere@gmail.com>
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <iostream>
diff --git a/src/extension/param/color.h b/src/extension/param/color.h
index f3b44b412..c2d3c2ccb 100644
--- a/src/extension/param/color.h
+++ b/src/extension/param/color.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef SEEN_INK_EXTENSION_PARAMCOLOR_H__
 #define SEEN_INK_EXTENSION_PARAMCOLOR_H__
 /*
@@ -5,7 +6,7 @@
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/description.cpp b/src/extension/param/description.cpp
index 5726962c7..154c172df 100644
--- a/src/extension/param/description.cpp
+++ b/src/extension/param/description.cpp
@@ -1,8 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifdef linux  // does the dollar sign need escaping when passed as string parameter?
diff --git a/src/extension/param/description.h b/src/extension/param/description.h
index 84e402890..822370b82 100644
--- a/src/extension/param/description.h
+++ b/src/extension/param/description.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef __INK_EXTENSION_PARAMDESCRIPTION_H__
 #define __INK_EXTENSION_PARAMDESCRIPTION_H__
 
@@ -5,7 +6,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/enum.cpp b/src/extension/param/enum.cpp
index 277d05c44..5ba3e5772 100644
--- a/src/extension/param/enum.cpp
+++ b/src/extension/param/enum.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** \file
  * extension parameter for enumerations.
  *
@@ -11,7 +12,7 @@
  *
  * Copyright (C) 2006-2007 Johan Engelen
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/box.h>
diff --git a/src/extension/param/enum.h b/src/extension/param/enum.h
index 6d93c8e83..329bb26f9 100644
--- a/src/extension/param/enum.h
+++ b/src/extension/param/enum.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INK_EXTENSION_PARAMENUM_H_SEEN
 #define INK_EXTENSION_PARAMENUM_H_SEEN
 
@@ -12,7 +13,7 @@
  *
  * Copyright (C) 2006-2007 Johan Engelen
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <vector>
diff --git a/src/extension/param/float.cpp b/src/extension/param/float.cpp
index f71e716a0..2886ad792 100644
--- a/src/extension/param/float.cpp
+++ b/src/extension/param/float.cpp
@@ -1,9 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/adjustment.h>
diff --git a/src/extension/param/float.h b/src/extension/param/float.h
index ce92d8c28..c1d0f0f79 100644
--- a/src/extension/param/float.h
+++ b/src/extension/param/float.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INK_EXTENSION_PARAMFLOAT_H_SEEN
 #define INK_EXTENSION_PARAMFLOAT_H_SEEN
 
@@ -6,7 +7,7 @@
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/int.cpp b/src/extension/param/int.cpp
index d79b2916c..1c41c0834 100644
--- a/src/extension/param/int.cpp
+++ b/src/extension/param/int.cpp
@@ -1,9 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/adjustment.h>
diff --git a/src/extension/param/int.h b/src/extension/param/int.h
index e6f4ac3db..fac481267 100644
--- a/src/extension/param/int.h
+++ b/src/extension/param/int.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INK_EXTENSION_PARAMINT_H_SEEN
 #define INK_EXTENSION_PARAMINT_H_SEEN
 
@@ -6,7 +7,7 @@
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/notebook.cpp b/src/extension/param/notebook.cpp
index abfdee457..fed093f60 100644
--- a/src/extension/param/notebook.cpp
+++ b/src/extension/param/notebook.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** \file
  * Notebook and NotebookPage parameters for extensions.
  */
@@ -9,7 +10,7 @@
  *
  * Copyright (C) 2006 Author
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/adjustment.h>
diff --git a/src/extension/param/notebook.h b/src/extension/param/notebook.h
index 1d676615b..dd7154f06 100644
--- a/src/extension/param/notebook.h
+++ b/src/extension/param/notebook.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INK_EXTENSION_PARAMNOTEBOOK_H_SEEN
 #define INK_EXTENSION_PARAMNOTEBOOK_H_SEEN
 
@@ -12,7 +13,7 @@
  *
  * Copyright (C) 2006 Author
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/parameter.cpp b/src/extension/param/parameter.cpp
index 4b5a23a8d..a1afd6b18 100644
--- a/src/extension/param/parameter.cpp
+++ b/src/extension/param/parameter.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * Parameters for extensions.
  */
@@ -8,7 +9,7 @@
  *
  * Copyright (C) 2005-2007 Authors
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifdef linux  // does the dollar sign need escaping when passed as string parameter?
diff --git a/src/extension/param/parameter.h b/src/extension/param/parameter.h
index f784fdd01..c37d1539a 100644
--- a/src/extension/param/parameter.h
+++ b/src/extension/param/parameter.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * Parameters for extensions.
  */
@@ -7,7 +8,7 @@
  *
  * Copyright (C) 2005-2006 Authors
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INK_EXTENSION_PARAM_H__
diff --git a/src/extension/param/radiobutton.cpp b/src/extension/param/radiobutton.cpp
index cc539dd92..8c1d6a5f7 100644
--- a/src/extension/param/radiobutton.cpp
+++ b/src/extension/param/radiobutton.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** \file
  * extension parameter for radiobuttons.
  *
@@ -11,7 +12,7 @@
  * Copyright (C) 2006-2007 Johan Engelen
  * Copyright (C) 2008 Jon A. Cruz
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/box.h>
diff --git a/src/extension/param/radiobutton.h b/src/extension/param/radiobutton.h
index 5958be8a4..48d470a01 100644
--- a/src/extension/param/radiobutton.h
+++ b/src/extension/param/radiobutton.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INK_EXTENSION_PARAMRADIOBUTTON_H_SEEN
 #define INK_EXTENSION_PARAMRADIOBUTTON_H_SEEN
 
@@ -12,7 +13,7 @@
  *
  * Copyright (C) 2006-2007 Johan Engelen
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"
diff --git a/src/extension/param/string.cpp b/src/extension/param/string.cpp
index 5699a2fdb..6a3de1d04 100644
--- a/src/extension/param/string.cpp
+++ b/src/extension/param/string.cpp
@@ -1,9 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtkmm/adjustment.h>
diff --git a/src/extension/param/string.h b/src/extension/param/string.h
index 20bfd849c..195496ba3 100644
--- a/src/extension/param/string.h
+++ b/src/extension/param/string.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INK_EXTENSION_PARAMSTRING_H_SEEN
 #define INK_EXTENSION_PARAMSTRING_H_SEEN
 
@@ -6,7 +7,7 @@
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
  *   Jon A. Cruz <jon@joncruz.org>
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "parameter.h"